Re: [time-nuts] Improving ocxo temp control

[Bill Hawkins]

My experience with industrial temperature control says there is always a
time lag between applying power to the heater and raising the
temperature at the thermistor. 

Because there is a lag, there is a gain beyond which the system
oscillates.

But I haven't read the non-referenced papers, so I could be wrong.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
kb8tq
Sent: Friday, May 18, 2018 9:46 PM

Hi

There are a number of papers out and about about the limits on OCXO
performance.
The bottom line is that coming up with a high resolution control circuit
is the easy part of the task.

Simple answer to the question: 

Set up a thermistor bridge and feed the difference into an op amp. Crank
up the gain on the op amp to whatever you feel comfortable running. 

Some simple numbers: 

Thermistor changes 3% / C
Single thermistor bridge changes 1.5% / C Output of the circuit will
change the oven by 150C from power off to full on Neglecting the scale
factors for simplicity Put in a gain of 100 on the op amp

So, the bridge moves 1% and the controller goes from full off to full
on. 
Crank in more gain "as required". The op amp isn't bothered until you
get into the millions.  

With the simplified numbers above, the circuit has a thermal gain of
150. Getting much past 300 with a single oven is unusual. 

Bob

> On May 18, 2018, at 2:03 PM, Gilles Clement
<clemg...@club-internet.fr> wrote:
> 
> Hi,
> I am trying to improve performance of an OCXO.
> Could you point me at a good design of a high resolution oven
temperature controler please ? Preferably analog.
> Thx much,
> Gilles.

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Re: [time-nuts] Anybody have suggestions for time related science fairprojects?

[Bill Hawkins]

Well, how about the frequency drift between a pendulum, a tuning fork,
and a crystal.
Atomic standards could be added depending on availability.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal
Murray
Sent: Thursday, May 10, 2018 11:56 PM
To: time-nuts@febo.com
Cc: Hal Murray
Subject: [time-nuts] Anybody have suggestions for time related science
fairprojects?


A few months ago, I was a judge for the county level middle school
science fair.  (I'm not very good at what they wanted, but that's a
different
problem.)

What sort of interesting time related experiments can a middle school
geek do?

Borrowing serious gear may not be off scale as long as a youngster can
run it.

-

An alternat meaning to the "nut" part of time-nuts:  ")
  https://www.snopes.com/fact-check/schools-removing-analog-clocks/


--
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Re: [time-nuts] Anybody have suggestions for time related science fairprojects?

[Bill Hawkins]

Um, time dilation by altitude if you have access to a mile high change.
Or subjective time dilation when a person is prevented from doing a task
on time.

Bill Hawkins 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal
Murray
Sent: Thursday, May 10, 2018 11:56 PM
To: time-nuts@febo.com
Cc: Hal Murray
Subject: [time-nuts] Anybody have suggestions for time related science
fairprojects?


A few months ago, I was a judge for the county level middle school
science fair.  (I'm not very good at what they wanted, but that's a
different
problem.)

What sort of interesting time related experiments can a middle school
geek do?

Borrowing serious gear may not be off scale as long as a youngster can
run it.

-

An alternat meaning to the "nut" part of time-nuts:  ")
  https://www.snopes.com/fact-check/schools-removing-analog-clocks/


--
These are my opinions.  I hate spam.



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Re: [time-nuts] Better quartz crystals with single isotope ?

[Bill Hawkins]

Good questions.

The one that bothers me is the magnetic levitation required to compare
the standard to anything. You can't put other materials inside the
vacuum bell with the standard. I looked up the paper, but it's behind a
$40 pay-wall.

Electromagnets will levitate permanent magnets, but the effect is not
stable, with the free magnet sliding out of the field. 
Diamagnetic materials will be stable, but the effect is so weak it would
require superconducting electromagnets. Quartz, as it happens, is
diamagnetic.

Now the problem is to apply identical levitation to dissimilar
materials. This would seem to require identical superconducting magnets
and identical levitated platforms. Identical currents can flow in the
levitating magnets simply by connecting them in series. In order for the
platforms to be identically levitated, they have to be an identical
distance from the levitating magnet. Measuring that to the required
precision could be a challenge.

Machining physical parts can be done to 10 E-6. That's not enough, so
the mechanism will require calibration. I suppose they could compare it
to the present platinum standard. Then there's the question of
calibration interval, and what to use as the standard. Counting
oscillations of atoms would be so much easier.

I think Rick's three points make this a non-starter. It's a case of
experts in metrology not having enough expertise in quarts resonators.

In answer to why they can't use 10 grams, the comparison has to be 100
times more accurate than that for 1000 grams.

Hope I haven't strayed too far off topic, and wasted my time.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard
(Rick) Karlquist
Sent: Sunday, April 22, 2018 4:11 PM
To: Discussion of precise time and frequency measurement; Bob kb8tq
Subject: Re: [time-nuts] Better quartz crystals with single isotope ?

On 4/22/2018 10:20 AM, Bob kb8tq wrote:

>> Do we know anybody in the quartz business who needs a really cool 
>> research project ?
> 
> You could put it on the list with the 1 Kg quartz resonator proposal
...
> 
> https://tf.nist.gov/general/pdf/2638.pdf 
> <https://tf.nist.gov/general/pdf/2638.pdf>
> 
> Also an offshoot of people thinking about the implications of all this
as it relates to resonators.
> 
> 
> Bob
> 

The cited article "must be true" because of its authors, I guess, but it
makes no sense to me.  They seem to be assuming that the resonant
frequency is inversely proportional to mass?  We all know three things:

1.  Frequency is inversely proportional to thickness.  Not mass.

2.  Frequency aging is affected by stress relaxation in well built
resonators.  The old idea that mass is gradually evaporating from the
resonator to the enclosure (glass enclosures) or mass is gradually
evaporating from the enclosure (metal enclosures) to depositing on the
resonator is simply obsolete in terms of current technology.
Thus again frequency is not a proxy for mass.

3. Resonators can "jump" in frequency without jumping in mass.

Given these facts, I am lost as how this is supposed to work.
Surely, the authors are well aware of the 3 items above.

Also, why does the resonator have to be a whole kilogram anyway.
If it weighed exactly 10 grams, couldn't you still compare it to a
kilogram using 100:1 leverage?

Can anyone straighten me out?

Rick
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Re: [time-nuts] 5062C (long shot) looking for ...

[Bill S]

I've got a couple of HP 5060-7202 extenders with 22 contacts. You're 
welcome to them if you think they might work.

Bill_S

On 4/21/2018 12:26 AM, Pete Lancashire wrote:

Does not hurt to ask, looking for ...

1259-1287 adapter

05062-60127 extender

05062-60128 extender

05062-60187 extender

05062-60126 2 x test cable



A8 10543-60013 5 MHz osc. assembly replacement 10543-00500
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Re: [time-nuts] Pulsars, clocks, and time nuts (Jim Palfreyman)

[Bill Hawkins]

It seems that pulsars are rotating stellar objects that have no reason
to change their rotation, except to decay.
Ruling out causes from the stellar object, one is left with things that
might be orbiting the object and their ability to absorb the pulse that
is aimed at us. One could move further out to the extremely low
probability that some interstellar object absorbed the pulse. This
doesn't explain the sawtooth, unless one of those orbiting bodies is
affecting the rotation rate of the pulsar, such as a binary star.

Disclaimer: I know very little about radio astronomy, but I've read a
lot of hard science fiction.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dana
Whitlow
Sent: Friday, April 13, 2018 8:39 AM
To: Tom Van Baak; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Pulsars, clocks, and time nuts (Jim Palfreyman)

Tom's discussion about pulsars brought back some memories...

Many pulsars exhibit skipped pulses.  And one curiosity that I didn't
see mentioned in Tom's discussion is that some pulsars even exhibit
behavior reminiscent of the "sawtooth jitter" so evident in the PPS
outputs of most GPS receivers.  See figures 12-11 & 12-12 in "An
Introduction to Radio Astronomy" (2nd edition) by Burke and
Graham-Smith.  The first ed also contains the basic plot (as figure 12-8
in this case), but whose explanation is not as up-to-date).

For a deeper treatment of pulsars, also see
  https://www.cv.nrao.edu/course/astr534/PDFnew.shtml
by Condon and Ransom (both of NRAO).

The above two references are the best Radio Astronomy tomes I've yet
seen..

Pulsar timing has been (and still is) a very big deal in radio
astronomy, as it is key to verification of certain points of Einstein's
General Theory of Relativity.

Here are two web sites in which audio recordings of various pulsar
sounds (made with larger radio telescopes) are presented.

https://www.youtube.com/watch?v=uHEVo-LkDrQ
(You may ignore the video part, even though it's "cute", but the audio
portion is a fine example of the pulse to pulse variations exhibited by
many pulsars, all wrapped up in one pulsar)

http://www.jb.man.ac.uk/pulsar/Education/Sounds/0329_stack.mp4
(I think this is the best overall site, giving quality recordings of a
fair number of different pulsars)

Dana






On Fri, Apr 13, 2018 at 2:54 AM, Tom Van Baak <t...@leapsecond.com>
wrote:

> Amazing news... 1.2.3.
>
> 1) Many of you know that pulsars are weird astronomical sources of 
> periodic signals. Some are so accurate that they rival atomic clocks 
> for stability! True, but I don't have a 100 foot antenna at home so 
> I'll take their word for it. Plus, you have to account for a myriad of

> PhD-level
> corrections: from earth's rotation to general relativity. And, like 
> quartz or rubidium clocks, pulsars drift (as they gradually slow 
> down). Precision timing is not easy. If you poke around the web you 
> can find numerous articles describing their detection and measurement 
> and exploring their use as reference clocks, both here and potentially
for deep-space timekeeping.
>
> 2) If you do a lot of clock measurement at home then you know the dark

> side of working with precision clocks. There are signal quality 
> issues, measurement resolution issues, reference stability 
> limitations, offset, drift, phase jumps, frequency jumps, missed or
extra cycles, glitches, etc.
> For example, quartz oscillators (depending on make / model / luck) can

> exhibit frequency jumps; i.e., without warning they just change 
> frequency without your permission. Ok, maybe not by a lot, but enough 
> to notice; perhaps enough to cause trouble to any naive GPSDO PID 
> algorithm that assumes steady state from the oscillator you thought
was stable.
>
> 3) Now the exciting part! Fellow time-nut Jim Palfreyman studies
pulsars.
> You've seen postings from him now and then over the years. It turns 
> out Jim is the first person to catch a pulsar in the act of a 
> frequency jump. After
> 3 years of continuous searching! This is really cool. Just amazing. 
> You can't get more time nutty than this. And it just got published in
Nature.
> It's a perfect never-give-up, i-eat-nanoseconds-for-breakfast, time 
> nut thing to do. I am so impressed.
>
> To quote Jim:
>
> On December 12, 2016, at approximately 9:36pm at night, my phone
> goes off with a text message telling me that Vela had glitched.
The
> automated process I had set up wasn't completely reliable - radio
> frequency interference (RFI) had been known to set it off in
error.
>
> So sceptically I logged in, and ran the test again. It was
genuine!
> The excitement was incredible and I stayed up all night analysing 
> the data.
>
> What surfaced w

Re: [time-nuts] Looking for IEEE-488 codes and formats for Datum 9700AT Programmable Time System

[Bill]

I have two of these with 488  interfaces.
Would appreciate any 488 info you get.
br...@otelco.net

-Original Message- 
From: Bob kb8tq

Sent: Saturday, April 07, 2018 10:27 PM
To: lee...@aol.com ; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Looking for IEEE-488 codes and formats for Datum 
9700AT Programmable Time System


Hi

Actually the manual is moot on any sort of remote control. The RS-232 
section refers you to an insert
in the back of the manual. I’d guess that the 488 stuff was done the same 
way.


Nasty question: Are you sure you have the 488 option installed?  It would 
not be the first piece of gear

produced that never really got a 488 firmware version …..

Bob

On Apr 7, 2018, at 11:11 PM, Tom Leedy via time-nuts  
wrote:



Hi:

I am looking for the IEEE-488 codes and formats for a Datum 9700AT 
Programmable Time System.  The 9700AT is a 1U time generator and 
translator with slots in the back that can accept option cards with 
various functionalities such as -488 and RS-232 interfaces, GPIO, and tape 
searches.  What I need is the character strings to output the time for 
the -488 interface.  The manual for the unit is here: 
http://www1.symmetricom.com/media/files/support/ttm/product-manual/man-9700at-9710.pdf

However, it is silent on the details of the -488 interface.

Any help would be appreciated and feel free to contact me offline.

Many thanks!

Tom Leedy
Clarksburg, MD


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Re: [time-nuts] TV Signals as a frequency reference

[Bill Byrom]

In the mid-1970's (when I was an EE student in college) I built a simple
setup to compare the US color burst signal (3.5795454.. MHz) from an old
vacuum tube color television set with a commercial surplus 5 MHz OCXO
(probably from Bliley). The color burst frequency was exactly:315/88 = (63 * 
5)/88  = 3.5795454.. MHz

So I built two  frequency dividers.  I think I used 7490 or 7492 TTL
IC's and a few gates. I divided the color burst signal from the TV set
by 63 to get a 56.81818.. kHz signal and compared the phase to the 5 MHz
oven oscillator divided by 88 (also 56.81818.. kHz). I had a surplus
Tektronix RM45A oscilloscope with a CA plug-in (24 MHz bandwidth) and a
surplus well-used analog chart recorder.
With this setup I could see the phase of the color burst signal of the
three major US networks (CBS, NBC, and ABC) when their local affiliate
station (Austin, Texas) was broadcasting a network feed. This was before
frame resynchronizers, so there was a glitch in the phase (and often a
frequency change which was easily detectable) when they switched away
from the network feed.
By late 1976 I was out of college at my first job (Rohdes-Groos
Laboratories), where I was the only engineer. My boss wanted us to
manufacture a low-cost frequency reference for calibration labs using
the color burst signal to discipline a local crystal oscillator. At that
time (mid to late 1970's) the three networks used rubidium or cesium
atomic frequency references to control their network feed color burst
and horizontal sync signals. NBS (later NIST starting in 1988) measured
the frequency error (and maybe the phase error - I forget) of each of
the networks on a daily basis, and published these in a document
released shortly after the end of each month (as I remember it). So you
could make local measurements and a few weeks later you could correct
for the measured error of that feed compared to the NIST reference. The
general idea was to average or curve fit the NBS errors for some
interval (a week or a month) and compare that against local measurements
you made during that interval. If the frequency error was stable or
linearly drifting you could make reasonable predictions for future
measurements, so you didn't have to wait for the NBS error reports to
get good results. We had a WWVB receiver and rubidium standard in our
office, so we could check the performance of our project.
A local company in Central Texas (unrelated to my company) developed a
simple product which detected the phase glitch in the color burst or
horizontal sync signal when the network feed phase changed. This was
used with other information to switch local programming (commercials,
etc.) into or out of the transmitted signal.
The first problem with using the network feeds to distribute frequency
was that at least one network started to look at the NBS frequency/phase
deviation reports and, thinking they were going to improve this process,
tweaked the magnetic field fine adjustment on their atomic standard in
an attempt to discipline the frequency. Of course, this removed the
ability to predict the behavior of that feed, since it might walk up or
down in frequency at any time the network tweaked their standard. So
everyone wanted the TV networks to stop tweaking their standards and
just let them slowly drift in a temperature stable environment.
But the worst problem was the introduction of frame resynchronizers.
This meant you were now measuring the local station frequency reference,
which wasn't usually all that good. So we cancelled the color burst
frequency standard project.--
Bill Byrom N5BB



On Sat, Mar 31, 2018, at 4:00 PM, Don Murray via time-nuts wrote:
> Dana...
>  
> Back in the day when out of studio news stories were
> shot on film, which was then processed at the studio 
> and broadcast from a "film chain" stations would lock
> their sync generators to the incoming network signal
> during network hours.  That allowed "clean" switching
> in and out of network programming.
>  
> When you were in the local programming portion of the
> day, the local sync generator would not be "looking" at
> the network signal for reference.  That was done because
> there may have been times when the AT microwave
> network was down for maintenance.  Obviously this was
> before the days of satellite delivery of the network services.
>  
> You are correct...  when the "Live Truck" came on the
> scene with instant on scene video, etc, the demand
> for frame syncs at each station went up.
>  
> Our first frame sync at, WTVJ in Miami, had been used
> at the Cape for some of the moon shots.  It was a huge
> box, occupying about two feet of rack space!
>  
> Later frame syncs, would drop in size to 1RU!
>  
> All those frame syncs were locked to our local
> master sync generator.  At one of our monitoring
> positions I could compare our local 3

[time-nuts] Leitch CSD-5300N

[Bill Baker via time-nuts]

Great news for owners of the wonderful old Leitch CSD-5300N master clocks.  
Many stations and academic facilities still use these fine clocks as they have 
SMPTE time code and impulse out as well as an audio time beep option.  They are 
still quite valuable on ebay.  The dial-up sync option is still supported by 
the National Research Council of Canada Time Service.  The dial in number is 
613 745-3900.  
Bill, W1BKR
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[time-nuts] Franklin Master Clock

[Bill Baker via time-nuts]

I have a relatively new Franklin Master Clock, model MP088-00A021 made in 
Philadelphia that just died.  It's a minute master with reversing polarity.  
Does anyone have a schematic?  The company is out of business after many years 
of making school clocks and no info on the web.  
Bill
w1bkr
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Re: [time-nuts] Quieting the HP-113AR Clock/Frequency Divider

[Bill Hawkins]

Here's another experience with a 103 crystal standard with the requisite
100 KC output and a 113 clock. I craved the clock because I'd seen it in
the Smithsonian precision time exhibit.

The 103 was certainly quiet, but the 113 was not, in spite of its heavy
cast aluminum case. The 1 KC stepping motor sings at a frequency that is
most sensitive to the ear. What were they thinking at HP? 

So I built an enclosure in an existing set of shelves. Quarter inch
paneling defined the enclosure, which was lined with thick fiberglass
insulation on all sides. The door was an insulated plywood panel that
had magnetic latches, so you could pull it loose to read the clock. You
could hardly hear it with the door closed.

Both the 103 and 113 were in the enclosure, reducing the temperature
changes typical of Minnesota. An external 28 volt power supply trickle
charged two 12V 7AH batteries with diodes to provide battery power when
the line went out. At the time, the power company was upgrading
underground service, so there were many opportunities to observe
switchover.

I'm sorry to say that I didn't keep detailed records of accuracy. IIRC,
the clock was within a few seconds of WWV at he New Year.

All in all, another fine learning experience. Sold the 103 and 113 after
a few years, and got into telephone GPS with a pair of HP Z3801A and a
16 foot plastic pipe mast for two HP conical antennas. Ended with the
Lucent stuff. Inquiries for recycling Lucent stuff welcome.

Bill Hawkins
bill.i...@pobox.com


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jeremy
Nichols
Sent: Saturday, March 17, 2018 9:39 PM
To: time-nuts@febo.com
Subject: [time-nuts] Quieting the HP-113AR Clock/Frequency Divider

Those of us with the 1960-vintage HP-113AR/BR Clock/Frequency Divider
know how noisy they are. The mechanical clock movement of my 113AR is
loud enough that I really don't want to be in the same room with it. I
don't know if the clocks are noisy from brand-new or if the mechanism
gets noisier as the various parts wear with age.

Here's how I quieted mine:
. Wrap the outer cabinet of the 113AR in stick-on automotive sound
deadener.
. Put the 113AR in a fully enclosed 4U rack cabinet.
. Stuff insulation into the cabinet so the 113AR is completely
surrounded except for the front panel.

Should anyone be interested, I can provide detailed notes, a shopping
list, and pictures. Total cost was about US$150 and would have been a
lot less if I could have found a used cabinet at the surplus store. 

Jeremy


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Re: [time-nuts] Looking for information on True Position GPSDO.

[Bill Byrom]

I don't have one, but I see some Time-nuts posts in 2017 about this
board and communications with it, such as:
https://www.febo.com/pipermail/time-nuts/2017-October/107096.html

https://www.febo.com/pipermail/time-nuts/2017-May/105124.html

I also found:
https://www.eevblog.com/forum/projects/gpsdo-loss-of-satellitesfix-troubleshooting/https://github.com/pigrew/trueposctrl
https://www.youtube.com/watch?v=c35RCqOOulY

--
Bill Byrom N5BB



On Sun, Mar 18, 2018, at 9:59 AM, John Green wrote:
> There is a small, about 3.5" by 4.5", GPSDO board being offered
> by several> sellers on eBay. I bought one from what looks to be the only US 
> based> source. It is identified as True Position, Inc., and had a small
> CTS OCXO> and Furuno GT8031 on board. I found hook up information in one of
> the Asian> vendor's ads. When it arrived, I hooked it up and waited for it
> to achieve> GPS lock. I left it over night, but it never locked. This morning,
> I sent a> message to the seller requesting to return it. I looked around
> on eBay to> see what the going price was and discovered that the US source
> was about> 1/3rd the price of the Asian vendors. I also noticed in one
>   listing where> the seller mentioned that it will not discipline the 10 MHz 
> unless you> entered a command by RS232. If you buy one, he will tell you what 
> the> secret command is. Does anyone, perchance happen to know the secret
> command? And, would you be willing to share? This isn't a bad looking> little 
> board. I was thinking of pulling the little CTS oscillator and> replacing it 
> with something better. The fact that you have to tell
> it to do> its thing is something of a bummer, but I think I can live with it.
> 
> <https://www.avast.com/sig-email?utm_medium=email_source=link_campaign=sig-email_content=webmail_term=icon>>
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Re: [time-nuts] Need a Watch Recommendation

[Bill Byrom]

On Wed, Mar 14, 2018, at 6:53 PM, Dr. David Kirkby wrote:
> What is the most demanding task one would use a wrist watch for? 

It depends on your job or hobby. 

During the Apollo 13 rocket burn before their emergency re-entry, Jack
Swigert used a wrist watch to time the retrorocket burn which was
manually controlled by Jim Lovell. Their normal capsule chronometer was
inoperative. This was mostly a differential (time interval) timing
measurement.
If you needed to determine your location (longitude) and all you had
was a wristwatch and a sextant (and software or a table with certain
information), the accuracy of the distance calculation would depend on
the absolute time accuracy of the watch. At the equator the longitude
error due to time error is (40,075.16 km/day) / (86,400 sec/day) =
463.8 m/sec.
Amateur astronomers need to know time accurate to about a second or
better for accurate osculation observations.
Amateur Radio nets and phone, Skype for Business, or WebEx conference
calls usually start pretty close to the scheduled time. In some cases
people start wondering if the organizer is delayed after about 15 to
30 seconds.--
Bill Byrom N5BB



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Re: [time-nuts] Terrestrial GPS

[Bill Byrom]

Have you noticed that your mobile devices (smartphone, iPad, tablet PC,
laptop PC) can often know your location when you inside a  building
shielding you from GPS satellites (or producing multipath confusing the
GPS receiver)? Here is a quick test you can do if you have a PC with no
GPS receiver but with WiFi capability:
Start up a browser and go to http://maps.google.com (which redirects to
https://www.google.com/maps/...) with a WiFi connection. Near the lower
right of the screen you should see the + - zoom buttons, and above these
a target icon. Click that target icon. If asked, enable location
finding. You may also need to enable your browser to release location
information.  In my case, I am now sitting near the middle of my house
and the laptop Windows 10 PC Google Maps locator places my location on
the street adjacent to my house, about 25 meters or so from my actual
location. My iPhone iOS map shows my location more closely (inside my
house) and it very accurately shows the location of the minivan I parked
in the driveway several hours ago (as "parked car").  My iPad also shows
my location within my house.
How do these devices know your location without GPS? Several methods are
used to produce a hybrid positioning system[1]:(1) Your IP address from your 
ISP. This gets me within a few km of my
location. See: https://www.iplocation.net/(2) WiFi positioning system[2] - 
This makes use of databases which
contain the geographic location of WiFi access points. The data is
collected by methods such as comparing the GPS receiver location
reports of mobile devices with the signal strength of access points.(3) 
Cellular radio location - Various techniques allow accurate
mobile phone tracking[3]. The signal strength and propagation
delay from cellular base stations allow moderately good
determination of location.
If you are in an area without GPS receiver coverage, your mobile device
or PC can determine the time using various techniques:(1) Crystal oscillator 
for short-term time stability.
(2) NTP: https://en.wikipedia.org/wiki/Network_Time_Protocol
(3) Cellular timing - cellular phone networks require very accurate
timing of the RF signals.
It would be hard to place terrestrial transmitters on the GPS satellite
frequencies without dynamic range and other problems, and of course
someone could use this technique to jam GPS reception in an area. But
several terrestrial geolocation and timing dissemination systems have
been proposed, and some limited deployment has been 
achieved.https://en.wikipedia.org/wiki/NextNav
http://www.nextnav.com/technology
http://esatjournals.net/ijret/2013v02/i04/IJRET20130204031.pdf
https://spectrum.ieee.org/tech-talk/telecom/wireless/us-master-clock-keepers-test-ground-alternative-to-gps--
Bill Byrom N5BB



On Tue, Mar 13, 2018, at 5:17 PM, Stewart Cobb wrote:
> Peter Reilley suggests a backup to GPS using terrestrial
> transmitters. This> idea has been around since the early days of GPS. The 
> terrestrial
> transmitters were called "pseudo-satellites", or "pseudolites"
> for short.> The big problem with this idea is that the GPS signal format has
> a narrow> dynamic range. The signal strength from a terrestrial
> transmitter varies> widely (inverse square law) from positions near the 
> transmitter to
> positions far away. The variation in any practical system is
> larger than> the GPS signal format can handle. This is called the "near-far
> problem".> For an extensive discussion of the pseudolite concept, including 
> the
> near-far problem, see my dissertation. You can find it with a
> web search> for my full name and the word "pseudolites".
> 
> Cheers!
> --Stu
> _
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> and follow the 
> instructions there.


Links:

  1. https://en.wikipedia.org/wiki/Hybrid_positioning_system
  2. https://en.wikipedia.org/wiki/Wi-Fi_positioning_system
  3. https://en.wikipedia.org/wiki/Mobile_phone_tracking
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Re: [time-nuts] Recommendations for Mains Power Monitor / Logger

[Bill Hawkins]

Well, this synchronization follows the laws of physics. If the energy
generated doesn't equal the energy consumed, then the frequency may
raise or lower. This is for steam turbines. If the energy come front an
inverter from a DC tie line, as it does from the four regions in the US,
the frequency is anything it wants to be. Well not quite. Raising the
inverter frequency a hair causes the tie line to be the major source of
energy. One could track the use of energy by frequency to make
investment decisions in manufacturer's stocks.

The problem with zero crossing triggers is the amount of noise caused by
solid state power supplies and by tap changing by the power companies to
match loads to minimize transmission losses. I've considered using a
mechanical synchronous motor and slotted wheel to eliminate noise near
the zero crossing, but now that I am 80, I don't give a darn, you see.

Bill Hawkins


 -Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
Albert via time-nuts
Sent: Saturday, March 10, 2018 5:58 PM

 There isn't a whole lot of justification for measuring power line
frequency.  We are all synchronized (in the first world at least) and
while there are phase instabilities, it's seldom the frequency varies
enough to overcome the noise.
As for voltage, it's much more steady than several years ago.  Most
people have 122 Volts, give or take a couple.  Again, not a whole lot of
purpose in recording it.
The distortion is another story.  It's never quite sinusoidal but there
is also some random noise picked up between the generators and the
load.  Looking at the 'scope it's seldom it looks like the textbook
picture of a sine wave.  Chances are most distortion is odd harmonic.
Distortion probably mostly comes from loads which are not resistive,
such as switching power supplies, rectifiers, fluorescent lamps, and
such.  These loads draw currents that are not sinusoids and so cause
voltage drops that are also of that character.
Bob

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Re: [time-nuts] Frequency deviations in Europe affect clocks

[Bill Hawkins]

Well, if you don't pay your bills, the power company can't afford the
fuel required to keep up with demand.
Stability of the system frequency requires a balance between supply and
demand. If the demand exceeds supply then the generators must slow down.
In a synchronous network, all generators must slow down to reduce strain
on the network. If strain is exceeded, circuit breakers pop until the
demand equals supply. So if a part of the network has to slow down from
lack of fuel, then the entire network has to slow down to prevent
popping circuit breakers until demand power equals supply.

Hope that helps,
Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of David
G. McGaw
Sent: Thursday, March 08, 2018 11:01 PM
Subject: Re: [time-nuts] Frequency deviations in Europe affect clocks

Can someone please explain why not paying your bills causes the grid and
therefore the clocks to slow down?  None of the reports, either for the
technical or lay person, give a reason.

David N1HAC



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Re: [time-nuts] Frequency deviations in Europe affect clocks

[Bill Woodcock]

> On Mar 8, 2018, at 6:39 AM, Jean-Louis Rault <f6...@orange.fr> wrote:
> 
> A picture of my own microwaves oven, this 8th of march, near Paris, France .


https://preview.entsoe.eu/news/2018/03/06/press-release-continuing-frequency-deviation-in-the-continental-european-power-system-originating-in-serbia-kosovo-political-solution-urgently-needed-in-addition-to-technical/


    -Bill



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Re: [time-nuts] Need a Watch Recommendation

[Bill Beam]

Even my pre civil war pocket watches should be good enough
for your needs.  Better than a minute/day.

But for some (many) time-nuts it's about wants, not needs.

My clocks and watches that can be heard across the room qualify
me as old school time nut.  (My DOB qualifies me as just plain old.)


On Mon, 5 Mar 2018 03:20:40 -0500, Don Murray via time-nuts wrote:

>Hi Bill...
>- 
>My Rolex GMT Master was stolen back in '75,
>so no luck on that. - Rolex is a bit pricey for
>my needs.
>- 
>My Seiko CQ001M, one of the first Seiko Digitals,
>was amazing. - Over the time I had it, it varied less
>than plus/minus 1 second against WWV. - I carried
>a Radio Shack Time Kube with me, when I was
>challeneged, as to the accuracy of that watch! - 
>It died many- years later, and the replacement 
>innards were- totally "loose!"
>- 
>Yes, I think that Time Kube qualifies me as a
>"Old School Time Nut! - ;-)
>- 
>TNX Bill.
>- 
>73
>Don
>W4WJ
>- 
>In a message dated 3/5/2018 1:31:04 AM Central Standard Time, wb...@gci.net 
>writes:

>- 
> My 37 year old Rolex day-date gains less than 2 sec/day compared to GPS clock.
>Rolex standard is +6/-2 sec/day.

>Regards, NL7F

>On Mon, 5 Mar 2018 01:38:06 -0500, Don Murray via time-nuts wrote:

>>Hello Time Nuts...


>>-n++
>>After 6 years of no troubles, in sync with WWV any
>>hour of the day, flawless transfer between
>>standard and daylight time my Stauer Titanium
>>Atomic wristwatch bite the dust a year ago.
>>-n++
>>Since then, Stauer has sent me three replacements,
>>each with some type of problem. -n++
>>-n++
>>So it looks as if I am in need of a new wristwatch,
>>which will give me some kind of time accuracy.
>>-n++
>>So, Time Nuts... -n++any suggestions or recommendations?
>>-n++
>>TNX
>>-n++
>>73
>>Don
>>W4WJ
>>___
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>>and follow the instructions there.



>Bill Beam
>NL7F



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Bill Beam
NL7F



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Re: [time-nuts] Need a Watch Recommendation

[Bill S]

I wore a Casio "Atomic" watch and it set itself reliably for many years 
until very recently. They are still available.  I've replaced it with a 
Seiko Solar "Radio" watch which I understand has a better wwvb receiver 
in it. Haven't worn it yet so I'm not sure how it will perform but I've 
heard good comments.

Bill

On 3/5/2018 1:38 AM, Don Murray via time-nuts wrote:

Hello Time Nuts...


  
After 6 years of no troubles, in sync with WWV any

hour of the day, flawless transfer between
standard and daylight time my Stauer Titanium
Atomic wristwatch bite the dust a year ago.
  
Since then, Stauer has sent me three replacements,

each with some type of problem.
  
So it looks as if I am in need of a new wristwatch,

which will give me some kind of time accuracy.
  
So, Time Nuts...  any suggestions or recommendations?
  
TNX
  
73

Don
W4WJ
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.



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Re: [time-nuts] Need a Watch Recommendation

[Bill Beam]

My 37 year old Rolex day-date gains less than 2 sec/day compared to GPS clock.
Rolex standard is +6/-2 sec/day.

Regards, NL7F

On Mon, 5 Mar 2018 01:38:06 -0500, Don Murray via time-nuts wrote:

>Hello Time Nuts...


>- 
>After 6 years of no troubles, in sync with WWV any
>hour of the day, flawless transfer between
>standard and daylight time my Stauer Titanium
>Atomic wristwatch bite the dust a year ago.
>- 
>Since then, Stauer has sent me three replacements,
>each with some type of problem. - 
>- 
>So it looks as if I am in need of a new wristwatch,
>which will give me some kind of time accuracy.
>- 
>So, Time Nuts... - any suggestions or recommendations?
>- 
>TNX
>- 
>73
>Don
>W4WJ
>___
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Bill Beam
NL7F



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Re: [time-nuts] Replacement A9 boards for the HP 5065A

[Bill Hawkins]

Group,

After 40 years of doing PID control for industrial processes, I'm used
to an error tolerance of 10E-3. So I couldn't understand an integrator
with a 10 K resistor and a 5 mfd capacitor.

But this is time nuts, and the tolerance is more like 10E-13.

An integrator as a controller takes any deviation from zero error
voltage and moves the output in a direction that will return the error
to zero.

In this case, 10 K is the practical lower limit to the input resistor
for the desired time constant, with 5 mfd as a practical upper limit.
Any current flowing in that resistor changes the value of zero error,
which causes the output to move when the actual error is zero. This
makes the frequency wander. The current can come from the opamp bias or
capacitor leakage when the output is not zero.

Similarly, a change in the opamp zero offset causes a false error which
makes the output move when it shouldn't.

So I withdraw my comment about aluminum electrolytics, which was made
without a timenuts perspective.

Determining maximum error currents and offsets is simply a matter of
mathematics, which is left as an exercise for the student.

Regards,
Bill Hawkins

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Re: [time-nuts] Replacement A9 boards for the HP 5065A

[Bill Hawkins]

Corby

A time constant is calculated from R and C.

If 50 milliseconds is the correct number, R for 5 mfd is 10,000 ohms.

You could use an aluminum electrolytic for the capacitor.

Can you tell us where the 50 ms number came from?

Regards,
Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of
cdel...@juno.com
Sent: Saturday, February 24, 2018 5:45 PM
To: time-nuts@febo.com
Subject: [time-nuts] Replacement A9 boards for the HP 5065A

Hi,

I'm working to make some replacement A9 boards for the HP 5065A to the
new style schematic.

Will share the Gerber file when done.

The integrator capacitor is a 1986 vintage TRW 5.0ufd 50V 10%
.42"DX1.0"L axial.

Of course it has an HP part number and no manufactures #.

Any guess as to what type it is?

Polycarbonate, polypropylene, ???

Just wanting to find a good modern replacement for its use. (Integrator
with a 50ms time constant.)

Thanks,

Corby

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Re: [time-nuts] eBay GPS antenna test.

[Bill Hawkins]

Learned tonight that J. P. Morgan got his start by buying 25 K defective
rifles for %3.50 each and selling them to the Army for $25 each. You
have no reason to trust a listing.

Bill Hawkins

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
kb8tq
Sent: Tuesday, February 13, 2018 12:04 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] eBay GPS antenna test.

Hi


> On Feb 13, 2018, at 12:06 PM, Clint Jay <cjaysh...@gmail.com> wrote:
> 
> Agreed but stock numbers on boxes and packets  are usually Arabic 
> numerals or a barcode. It's also possible the seller used a stock 
> image which can be copied and pasted into Google web search to track 
> down the maker or at least a distributor who has data.

The seller did post a number of images for the part that was listed. The
gotcha is that the part that arrived is not labeled the same way as the
part that was listed.
Since the device also has issues, the big question is if it has any
connection to the part in the listing at all. 

The seller seems to have been doing GPS stuff for a while. He also has a
very good approval rating. My guess is: this isn't the first time he's
seen a bump in the road. I'd bet he's got the ability to check this and
that out to see what is what. 
The seller *does* matter when you buy this stuff. That's true no matter
what you are getting. No matter how good they are, problems do come up.
The question is always how well they address them. We tend to dump
pretty hard on these guys. I'm not sure that's always warrantied. 

Bob


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Re: [time-nuts] True Time Nut Mission: NASA's Deep Space Atomic Clock (DSAC)

[Bill Byrom]

Yeah -- delays happen. The DSAC is part of the US Air Force STP-2 program. 
STP-2 launch was awarded to SpaceX in December, 2012. But the Falcon Heavy only 
completed it's first launch earlier this week, and instead of sending a 
customer payload they send a Tesla to past the orbit of Mars. 

Correcting my earlier post, the new launch date for STP-2 appears to be "no 
earlier than" June, 2018. I'm relying on this source for launch estimates:
https://spaceflightnow.com/launch-schedule/
--
Bill Byrom N5BB

On Fri, Feb 9, 2018, at 7:54 AM, jimlux wrote:
> On 2/8/18 8:55 PM, Bill Byrom wrote:
> > After the successful Falcon Heavy launch earlier this week, it appears that 
> > the Deep Space Atomic Clock (DSAC) is now scheduled to go up in June 2018 
> > on a Falcon Heavy carrying the US Air Force STP-2 test payloads.
> > https://www.nasa.gov/feature/goddard/2018/nasa-tests-atomic-clock-for-deep-space-navigation
> > 
> > For a fun video about this project suitable for non-time-nuts, see:
> > https://www.nasa.gov/mission_pages/tdm/clock/sammy-the-second.html
> > 
> 
> "The Deep Space Atomic Clock is being readied for flight next year. 
> Moving hardware from the laboratory to space meant conquering a number 
> of technological challenges."
> 
> A number of really hard technological challenges. Aside from taking a 
> bench full of gear and squeezing it down to a few liters.
> 
> Note the date on an earlier note:
> "DSAC is scheduled for launch in mid-2016"
> 
> 
> 
> 
> >> Date: Tue, 12 Jan 2016 17:31:26 -0600
> >>
> >> Upcoming Event: Deep Space Atomic Clock
> >> Jan. 14, 2016, at 7 p.m. PT (10 p.m. ET, 0300 UTC)
> >> You can watch this event via USTREAM:  http://www.ustream.tv/NASAJPL2
> >>
> >> Speakers:
> >> Todd Ely, DSAC Principal Investigator, JPL
> >> Allen H. Farrington, DSAC Project Manager, JPL
> >> http://www.nasa.gov/mission_pages/tdm/clock/clock_overview.html#.VpWMgK9OKK0
> >> Atomic clocks are an integral, yet almost invisible component of modern
> >> life.
> >> For space exploration, they have been the foundational frequency
> >> standard for NASA's Deep Space Network. NASA's Deep Space Atomic Clock
> >> (DSAC) Technology Demonstration Mission, led by the Jet Propulsion
> >> Laboratory, has been maturing the latest Atomic Clock technologies into
> >> a smaller package, suitable for installation on a variety of deep space
> >> probes to enhance navigation precision and gravity science across the
> >> solar system.
> >> 
> >> DSAC is scheduled for launch in mid-2016.
> >> Satellite being built by Surrey Satellite Technologies USA, Englewood,
> >> CO
> >>
> >>
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Re: [time-nuts] True Time Nut Mission: NASA's Deep Space Atomic Clock (DSAC)

[Bill Byrom]

After the successful Falcon Heavy launch earlier this week, it appears that the 
Deep Space Atomic Clock (DSAC) is now scheduled to go up in June 2018 on a 
Falcon Heavy carrying the US Air Force STP-2 test payloads.
https://www.nasa.gov/feature/goddard/2018/nasa-tests-atomic-clock-for-deep-space-navigation

For a fun video about this project suitable for non-time-nuts, see:
https://www.nasa.gov/mission_pages/tdm/clock/sammy-the-second.html

--
Bill Byrom N5BB

On Tue, Mar 21, 2017, at 11:36 PM, Bill Byrom wrote:
> NASA's Deep Space Atomic Clock test mission is moving toward a late-2017
> launch (don't all projects slip?). The DSAC was just integrated with the
> spacecraft. The clock uses a ~40.5 GHz hyperfine transition of mercury
> ions. This steers an ovenized crystal USO (Ultra Stable Oscillator) from
> FEI with 1-100 sec stability <2e-13 and drift <1e-10/day. A GPS receiver
> is also on board:
> https://www.jpl.nasa.gov/news/news.php?feature=6784
> 
> NASA information about the DSAC applications at:
> https://www.nasa.gov/mission_pages/tdm/clock/index.html
> 
> Expected DSAC performance (2014 paper). This paper claims an estimated
> Allan Deviation of <1e-14 (perhaps 3e-15) at a one day interval when in
> space:
> https://www.researchgate.net/publication/260036335_Expected_Performance_of_the_Deep_Space_Atomic_Clock_Mission
> 
> 
> Here are the latest two papers I can find (from Feb 2016):
> 
> ** Deep Space Atomic Clock Technology Demonstration Mission Onboard
> Navigation Analog Experiment:
> https://www.researchgate.net/publication/293648952_Deep_Space_Atomic_Clock_Technology_Demonstration_Mission_Onboard_Navigation_Analog_Experiment
> 
> ** Preliminary Investigation of Onboard Orbit Determination using Deep
> Space Atomic Clock Based Radio Tracking:
> https://www.researchgate.net/publication/293648187_Preliminary_Investigation_of_Onboard_Orbit_Determination_using_Deep_Space_Atomic_Clock_Based_Radio_Tracking
> 
> --
> Bill Byrom N5BB
> 
> - Original message -
> From: Gregory Beat <w...@icloud.com>
> To: time-nuts@febo.com
> Subject: [time-nuts] True Time Nut Mission: NASA's Deep Space Atomic
> Clock (DSAC)
> Date: Tue, 12 Jan 2016 17:31:26 -0600
> 
> Upcoming Event: Deep Space Atomic Clock
> Jan. 14, 2016, at 7 p.m. PT (10 p.m. ET, 0300 UTC)
> You can watch this event via USTREAM:  http://www.ustream.tv/NASAJPL2
> 
> Speakers: 
> Todd Ely, DSAC Principal Investigator, JPL
> Allen H. Farrington, DSAC Project Manager, JPL
> http://www.nasa.gov/mission_pages/tdm/clock/clock_overview.html#.VpWMgK9OKK0
> Atomic clocks are an integral, yet almost invisible component of modern
> life. 
> For space exploration, they have been the foundational frequency
> standard for NASA's Deep Space Network. NASA's Deep Space Atomic Clock
> (DSAC) Technology Demonstration Mission, led by the Jet Propulsion
> Laboratory, has been maturing the latest Atomic Clock technologies into
> a smaller package, suitable for installation on a variety of deep space
> probes to enhance navigation precision and gravity science across the
> solar system.
> 
> DSAC is scheduled for launch in mid-2016.  
> Satellite being built by Surrey Satellite Technologies USA, Englewood,
> CO
> 
> 
> Sent from iPad Air
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[time-nuts] Heathkit GC 1000 Most Accurate Question

[Bill Baker via time-nuts]

I own a Heathkit GC 1000 Most Accurate Clock.  It's in terrific shape but not 
used for many years.  It has stopped locking up to WWV and sometimes freezes 
up.  Can any of our "nuts" repair it?  Anyone want to buy it?

Bill, w1...@aol.com
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Re: [time-nuts] PBS, Tue evening, The Secret of Tuxedo Park

[Bill Metzenthen]

It also worked in Australia last night.  I watched a few minutes and 
decided to watch the rest today.  Unfortunately, it is now geo-blocked 
:-(  It's also blocked on the PBS site.



On 18/01/18 02:09, Heinz Breuer wrote:

The link worked perfectly in Germany.

vy 73 Heinz DH2FA, KM5VT

Von meinem iPhone gesendet


Am 17.01.2018 um 15:48 schrieb EB4APL <eb4...@gmail.com>:

Joe,
Thank you for the pointer. The regular web site don't allow the series to be 
viewed outside USA.

73 de Ignacio, EB4APL



El 17/01/2018 a las 2:47, Joseph Gray escribió:
If you want to watch this episode online, go here:
http://video.unctv.org/video/3008204310

This is the UNC Public TV web site.

Joe Gray
W5JG




On Tue, Jan 16, 2018 at 2:28 PM, Bill Tracey <b...@ewjt.com> wrote:

To record OTA television I use an HDHomeRun :
https://www.silicondust.com/hdhomerun/

I'll grab tonight's run of The Secret of Tuxedo Park

Cheers,

Bill

At 09:04 AM 1/16/2018, you wrote:


I can't stress enough how important Loomis was to the history of precise
timekeeping in early radio, telephone, pendulum clock, quartz oscillator
era. And for those of us who still have Loran-C receivers can thank him
(Loomis Radio Navigation -> LRN -> Loran).
.

If someone knows how to record any time/clock/navigation parts of PBS
show for non-US viewers let me know, off-list.

/tvb

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Re: [time-nuts] PBS, Tue evening, The Secret of Tuxedo Park

[Bill Tracey]

To record OTA television I use an HDHomeRun : 
https://www.silicondust.com/hdhomerun/


I'll grab tonight's run of The Secret of Tuxedo Park

Cheers,

Bill

At 09:04 AM 1/16/2018, you wrote:
I can't stress enough how important Loomis was to the history of 
precise timekeeping in early radio, telephone, pendulum clock, 
quartz oscillator era. And for those of us who still have Loran-C 
receivers can thank him (Loomis Radio Navigation -> LRN -> Loran).

.

If someone knows how to record any time/clock/navigation parts of 
PBS show for non-US viewers let me know, off-list.


/tvb


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Re: [time-nuts] AM vs PM noise of signal sources

[Bill Hawkins]

Thank you, Charles.

What a clever way to minimize the power dissipation in Q4 with the
components of the day.

A switching regulator without the steep (and noisy) transients of
today's switchers.

Bill Hawkins 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles
Steinmetz
Sent: Monday, January 08, 2018 10:21 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] AM vs PM noise of signal sources

Bill wrote:

> What does the unijunction 2N2646 do in the oven controller?

For the following discussion, you need to refer to the *corrected*
schematic I mentioned in my last post.  If you are looking at the HP
schematic, you will wonder how the hell it works (and it wouldn't, if HP
actually built them as they drew it).

The 10544 oven control circuit uses pulse-width modulation to control
the heater in a "bang-bang" manner rather than a smooth proportional
manner.  UJT A3Q3 forms a relaxation oscillator (along with A3C1 and
A3R10), with a period of ~250uS (frequency ~4kHz) and a voltage span
from ~0v to ~8v.

This positive-going ramp is applied to the base of Darlington A3Q2
(MPSA12), which is 1/2 of a differential pair current switch along with
A3Q1 (2N3904).

The thermistor and associated op-amp circuitry set a threshold voltage
between ground and about 7v at the base of Q1.  After the relaxation
oscillator resets to ~0v, current flows through A3Q1 and A3R8, pulling
the base of Darlington A3Q4 negative and turning it on to saturation. 
The collector of A3Q4 therefore applies essentially the full oven heater
supply voltage from Pin 14 (nominally 24v) to the high side of the
heater.

The oscillator voltage ramps positive toward its ~8v maximum (the
trigger point of UJT A3Q3).  When the emitter of A3Q2, which is two
diode drops below the ramp voltage, exceeds the voltage at the emitter
of Q1 (as set by the thermistor and A3U1), Q2 steals the current that
has been flowing in A3Q1 and turns Darlington switch A3Q4 off, which
interrupts the current flowing through the heater.  Some time later
(about 250uS after the previous reset), the oscillator voltage reaches
the trigger point of the UJT and it resets the voltage on A3C1 to ~0v
and the cycle begins again.

Thus, every ~250uS the heater is on for a time (set by the thermistor
circuitry) and off for the remainder of the ~250uS.  This switching
action can be seen at the "Oven Monitor", Pin 11 (but note that the
instrument may have a capacitor to ground on the mother card side of the
oven monitor, to integrate the switching waveform for use by the
instrument's health monitor).

Best regards,

Charles


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Re: [time-nuts] AM vs PM noise of signal sources

[Bill Hawkins]

Charles,

What does the unijunction 2N2646 do in the oven controller?

Bill Hawkins
 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles
Steinmetz
Sent: Monday, January 08, 2018 7:50 AM

Also, note that the HP schematics of the 10544 have some errors that
were (as far as I can tell) never corrected by HP.  I posted a corrected
and annotated schematic to Didier's site (ko4bb.com).  Here's a link:

<http://www.ko4bb.com/getsimple/index.php?id=download=HP_Agilent/HP
_10544_Crystal_Oven_Oscillator/HP_10544A_schematic_further_corrected_and
_annotated.pdf>

Best regards,

Charles


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Re: [time-nuts] Skilled Math Editor(s) Needed

[Bill Hawkins]

Friends in time,

Perry has apparently reached a major change in his life, perhaps because
of a doctor's diagnosis - but there are zillions of other reasons. It
seems to me that he is looking for someone to pick up his project and
run with it.

Advising him on the ways he could continue is probably not useful. He
needs someone to take the baton and take it further.

I say this as one who has downsized by 75% in order to move into a life
care community after my wife and I had cancer scares and no long term
care insurance.

A cousin was the copy editor for Gone With the Wind and other Doubleday
books. I seem to have inherited some of those genes. But I can't tell a
bad equation from a good one, and my French ended in High School.

Happy new year to the best list on the Internet.

Bill Hawkins



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Re: [time-nuts] Fluke/Pendulum PM6680/CNT-80 measurement instability/outliers

[Bill Byrom]

I have a few questions about your setup:
(1) What is the waveform shape you are measuring? Are you measuring a
square wave (or some other duty cycle waveform with fast rise and
falling edges)? Or is it a sinewave with low harmonic content?
(2) How is the counter voltage threshold set with respect to the peak
excursions? Is it set to the 50% point or near the bottom or top of the
waveform?
(3) How are you connecting the source to the counter input? Is it a 50
ohm RG-58 cable with BNC connectors? Are there any TEE connectors or
feed-through terminations? What is the cable impedance? You can easily
find 75 ohm cables with 75 ohm BNC connectors which will mate (with a
bit of difficulty in some cases) with 50 ohm female connectors. If you
have a 50 ohm counter impedance, a 75 ohm cable can cause difficulty.
(4) What is the output impedance of the source you are measuring?
(5) What is the input impedance of the counter (as it is set up for your
test)?

Here are a few observations about your results and my guess of the root
cause:
(A) As presented, the outliers are all positive offsets at multiples of
1 count (1, 2, 3, 4, 5, and 6 extra counts).
(B)  So the reason for the multiples of 1 Hz offset is obvious. With a 1
second gate interval, occasionally the counter measures 1 to 6 extra
counts.
(C) My belief is that you have some "noise" source or waveform
distortion which is generating the extra counts. It's a marginal case
where the interference is only occasionally counted. For example, the
noise or distortion might be passing through the counter input voltage
threshold without enough overdrive to reliably generate spurious counts. 
(D) If the source waveform is a square wave (or any pulse type waveform
with fast rising or falling edges) and there are any reflections due to
poor load match (the impedance of the counter not matching the coax
cable impedance), you will get a reflection. If the source is also
poorly matched (such as a low impedance drive from a digital logic
buffer), you will get a second reflection. This second reflection will
arrive at the counter input delayed from the original edge by twice the
propagation delay in the cable.
(E) If you use a 50 ohm RG-58 cable with a solid dielectric, the
velocity factor will be around 66%. So the propagation velocity is about
2 x 10^8 m/sec. This results in a round trip (2 m distance) delay of 10
ns.
(F) So if there is a mismatch at each end of the cable you will see a
second edge arriving at the counter input with a delay of 10 ns per
meter of cable length.  If it's a 100 MHz bandwidth counter, it will
count these extra transitions which pass through the input voltage
threshold.

Some potential causes for this condition:
(i) Poor source and load impedance match. If the counter only has a 1 M
input resistance, use an inline 50 ohm broadband terminator. I work for
Tektronix as an Application Engineer, and for over 50 years we have sold
inline 50 ohm terminators, such as this one:
https://www.bmisurplus.com/products/54615-tektronix-011-0049-01-termination-50-ohm-2-watt
You can also find many other sources for inline 50 ohm terminators. But
be careful -- if the counter already has a 50 ohm input impedance
(internal termination), use of an external 50 ohm terminator will result
in a 25 ohm combined impedance and a reflection. The same issue is found
at the source, but if you can get the load properly matched you don't
need to worry much about the source.
(ii) If the source is a pure sinewave (with low harmonic distortion) you
won't see this issue with matching, since there are no fast edges.
(iii) If the counter voltage threshold is set to a value near the upper
or lower waveform levels, it's easier to get spurious counts. Noise or
spurious ingress (broken or poor quality cable shield) can cause
problems. 
--
Bill Byrom N5BB

On Thu, Dec 14, 2017, at 10:58 AM, Attila Kinali wrote:
> Hi,
> 
> Just for fun, I've set up a PM6680 to measure a 10MHz OCXO (Trimble
> 34310).
> First I used the 10MHz output of an Trimble UCCM as reference (green
> trace
> in the attached file, drift removed, offset to match second trace),
> measuring
> with a gate time of 1s, one measurment every approximately 1.1s.
> As you can see, there are a couple of outliers, evenly spaced in 1Hz
> steps.
> To make sure, these weren't comming from the GPSDO (it's more noisy than
> I thought it would be), I switched to the PM6680's internal reference
> (violet trace) and got basically the same outliers.
> 
> If these outliers would have been only at 1Hz, I would have said they
> are metastability issues in the coarse counter (which runs at 10MHz).
> But getting metastability to last more 100ns is exteremly unlikely,
> yet I get outliers that are 6Hz(=600ns) out. The probability for
> metastability
> lasting that long is lower than being struck by a meteoritemuch
> lower!
> 
> So, the question is,

Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Bill Byrom]

Here is a project which mixed the Time Kube IF output back to 10 MHz for
use as a frequency (not time) 
standard:http://schematicsforfree.com/archive/file/Oscillators%20and%20Generators/Misc/10Mhz%20Frequency%20Standard%20Using%20Wwv.pdf
I believe that the Time Kube uses a 3-transistor mixer / 455 kHz IF
amplifier signal chain, followed by an IC audio amplifier. I would think
that the signal delay inside the receiver from antenna to audio output
would be a couple of hundred microseconds, much less than one cycle of
the demodulated audio “tick”.--
Bill Byrom N5BB



On Fri, Dec 8, 2017, at 07:13 AM, jimlux wrote:
> On 12/7/17 1:29 PM, Bill Hawkins wrote:
> >
>
> > So yes, this could be interesting for a hobbyist, but it won't add
> > anything to Science.
> > A MASER is overkill. Heck, so are Rubidium and Caesium.
> > A naked crystal will be rock solid compared to received WWV.
> >
> > OTOH, NTP has marvelous mathematical tricks to reduce Internet
> > propagation delay.
> > A scheme to reduce varying atmospheric delay would be useful,
> > if there> > weren't much better ways to get a standard frequency.
> >
>
> What you are talking about is "better ionosphere modeling", which is
> something that a lot of people have spent a lot of time and effort on,> 
> without a lot of success.  That said, there are some real time
> ionograms> out there that are fascinating to watch.  It doesn't take a very
> sophisticated receiver to receive the signals from a variety of
> ionosonde transmitters.
>
> Juha Vierinen has a variety of interesting software:
> http://www.sgo.fi/~j/gnu_chirp_sounder/
>
> Juha also has done stuff with measuring the frequency of beacon
> satellites
>
> http://www.sgo.fi/~j/jitter/web/
>
>
>
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Re: [time-nuts] Helmholtz Resonator and other Maintained Oscillators

[Bill Byrom]

The Q of Helmholtz resonators is derived here:
https://en.wikibooks.org/wiki/Acoustics/Flow-induced_Oscillations_of_a_Helmholtz_Resonator

Some Q measurements of bottles are described here:
https://math.dartmouth.edu/archive/m5f10/public_html/proj/ArainGolvach.pdf

--
Bill Byrom N5BB

On Sat, Dec 9, 2017, at 01:39 AM, Hal Murray wrote:
> 
> k8yumdoo...@gmail.com said:
> > The flex hose demonstration was interesting in that different regimes of
> > swinging speed resulted in oscillation in different modes.  I wonder why.
> 
> It depends on the speed of the air going through the tube.
> 
> https://www.youtube.com/watch?v=4aJ36-TlPD4
> 
> http://www.exo.net/~pauld/activities/AAAS/aaas2001.html
> http://www.exo.net/~pauld/summer_institute/summer_day13music/Whirly.html
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology

[Bill Hawkins]

One way to compare any WWV receiver to a local standard is to use the
PPS output of a standard against the PPS tick modulated on WWV. The tick
is five cycles of a one KHz signal derived from the master frequency.
See
https://www.nist.gov/pml/time-and-frequency-division/time-services/wwv-a
nd-wwvh-digital-time-code-and-broadcast-format

It will be a bit tricky to determine the onset of the first cycle amid
the noise on shortwave radio. A computation that determined that there
were just 5 cycles and worked backwards to determine the timestamp of
the beginning or middle of the tick could then allow calculation of the
offset between the standard PPS and the tick. Limit of accuracy might be
100 microseconds. 

Years ago, I had a standard calibrator made by Lavoie that had a vacuum
tube WWV receiver. IIRC, the WWV carrier caused a circular sweep on a 2
inch CRT. The sine wave from a standard modulated the intensity of the
circular trace, so that a bright half moon appeared on the CRT and
rotated at the error rate between the two frequencies. On several
evenings the dominant signal varied between WWV and WWVH (identified by
the voice broadcasts). Here in Minneapolis the phase difference between
the two stations was about 180 degrees, causing the bright arc on the
CRT to change sides.

So yes, this could be interesting for a hobbyist, but it won't add
anything to Science.
A MASER is overkill. Heck, so are Rubidium and Caesium.
A naked crystal will be rock solid compared to received WWV.

OTOH, NTP has marvelous mathematical tricks to reduce Internet
propagation delay.
A scheme to reduce varying atmospheric delay would be useful, if there
weren't much better ways to get a standard frequency.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Patrick
Barthelow
Sent: Thursday, December 07, 2017 7:48 AM

Hello Friends,

I am picking up locally a couple of vintage analog Radio Shack SW time
cube radios, 70s vintage, 3 switchable SW frequencies.  Two types, the
one pictured and a Radio Shack model also that has WWV and Weather
channel VHF frequencies.
I am interested in an accurate bench test to compare the analog
shortwave radios time reporting hopefully UT-1 against other available
references.  For accuracy, and
repeatability.   Could eventually add an SDR to the mix, too.
The 5,10,15 mhz radios obviously are subject to the WWV Ft Collins site,
propagation distance delays, somewhat calculable, and the vagaries of
Ionospheric propagation, and, propagation delays between the antenna and
the measured tap point to the seconds ticks of WWV.   I have some
friends,
microwave professionals, who are also hams here in Auburn who may enjoy
doing a bench test, with published results, etc.  But wonder if anyone
else would be interested in borrowing a RS Timecube radio (and/or use an
SDR) and designing an accurate bench test against available modern
standards?
We are talking probably HUGE  UT-1 errors compared to what this group
plays with, and that is OK but I think still a worthwhile test,
especially if the errors using available and cheap equipment are
predictable, and repeatable.
https://forums.qrz.com/index.php?attachments/dscn1187-jpg.400844/

- %< - [snip of microwave stuff]

Best, 73,   Pat Barthelow AA6EG
apol <apollo...@gmail.com>lo...@gmail.com

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Re: [time-nuts] Lucent RFTG-u REF0-REF1 cable

[Bill Hawkins]

It's been a few years since I looked at this, but it seems to me that
the message from the receiver to the time processors included an
estimate of the reliability of the satellite data. That estimate depends
on satellites being in the predicted positions. If there is an error,
the time data is marked as invalid.

The old messages had 6 satellites, and the newer messages had 8. The
messages were identical, except that the newer message reported 2 more
satellites. An older time processor would not have been able to handle
the new 8 sat message. So, no, you can't mix old and new RFTG modules.

If this sounds like I know what I'm saying, you may be disappointed.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tim
Shoppa
Sent: Tuesday, November 14, 2017 9:53 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Lucent RFTG-u REF0-REF1 cable

Isn't info about what satellites are where, just eye candy and
irrelevant to a real GPSDO?

Tweaks to the elevation mask ought to be measurable in the PPS quality
(if they aren't then they're irrelevant).

Tim


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Re: [time-nuts] Fast rise time pulser

[BIll Ezell]

>Question. Rise and fall times are sub 40ps is that a typo in your email

No, those are the times provided in the test report that was sent with 
the pulser. Modern laser diode drivers are very fast (a MAX 3930 has a 
spec'd risetime of  ~25 ps).


--
Bill Ezell
--
The day Microsoft makes something that doesn't suck
will be the day they make vacuum cleaners.
Or maybe Windows 10.

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Re: [time-nuts] Fast rise time pulser

[BIll Ezell]

I rushed out and ordered one, and I have to say, I'm impressed.
The test report it came with states 34.4 ps risetime / 32.13 ps falltime 
8.6% overshoot measured with a Tek CSA 803A.
I hooked it up to my wonderful HP 54542 2 Gsamples/sec scope and got 
exactly what I would expect, 496 ps risetime 7.6% overshoot.


Screenshot attached, don't know if it will actually make it into the post.

This is exactly what I need for adjusting various of my time-related 
instruments.


--
Bill Ezell
--
The day Microsoft makes something that doesn't suck
will be the day they make vacuum cleaners.
Or maybe Windows 10.

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Re: [time-nuts] Better GPS coming to phones

[Bill Hawkins]

Sadly, it is not the phone users who will benefit. It is the advertisers
who use your location to send targeted ads.

Time marches on.

Bill Hawkins
 

-Original Message-
From: Mark Sims
Sent: Wednesday, September 27, 2017 6:54 AM

Broadcom has released a phone chip that supports L5 signals... claims 30
cm accuracy.Maybe you will soon be able to use your phone to set
your GPSDO location better...

Also the new iphones now support Galileo in addition to GPS and Glonass.

http://www.theregister.co.uk/2017/09/27/centimetre_accurate_gnss_chipset
_tested/

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Re: [time-nuts] Z3801A and Z38XX Issues

[Bill Hawkins]

Shouldn't that be 8 data bits?

Bill Hawkins

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard
Solomon
Sent: Saturday, September 09, 2017 4:24 PM

I downloaded and installed Z38XX, configured both the Port and Device to
the recommended parameters:


Data Rate:  19,200

Parity:  Odd

Data Bits:  7



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Re: [time-nuts] Very large X9.2 solar flare.

[Bill Byrom]

The Sun is very active this week! Lots of space weather warnings:

http://www.swpc.noaa.gov/news/g3-watch-7-through-9-september-2017-due-cme-effects

https://www.space.com/38057-sun-unleashes-decades-strongest-solar-flare.html

http://www.swpc.noaa.gov/news/s1-warning-extended-8-september0600-utc

http://www.arrl.org/news/space-weather-prediction-center-upgrades-geomagnetic-storm-watch-to-g3-strong
--
Bill Byrom N5BB

On Wed, Sep 6, 2017, at 04:19 PM, Alan Melia wrote:
> The flare has been and gone!...is this another case of journalists 
> mixing up a flare with a CME ?
> Alan
> G3NYK
> 
> - Original Message - 
> From: "Mark Sims" <hol...@hotmail.com>
> To: <time-nuts@febo.com>
> Sent: Wednesday, September 06, 2017 8:50 PM
> Subject: [time-nuts] Very large X9.2 solar flare.
> 
> 
> > It might be coming here...
> >
> > http://www.theregister.co.uk/2017/09/06/biggest_solar_flare_in_years_heading_our_way/
> >
> > You might want to break out your eclipse monitoring equipment...
> > ___
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[time-nuts] Huber 1399.17.0048

[Bill]

I acquired a Huber+Suhner  GPS / GSM   Type 1399.17.0048 antenna at a local 
Hamfest. It has N connectors.

Does anyone know its specs ?

Bill R



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Re: [time-nuts] GPS Antenna Feed Line Decision

[Bill Byrom]

For precision timing measurements, I would think that there would be
concern about the double reflections of a badly mismatched low loss
transmission line (such as using 75 ohm line in a 50 ohm environment).
The re-reflected signal will act similar to  multipath (as a delayed
aggressor) on all satellite signals equally. The impedance mismatch
delayed reflection aggressor could aggravate timing errors due to
changes in temperature or stress in the cable. Whether this is important
for you depends on how time-nutty you want to get.

See these papers:

Effects of Antenna Cables on GPS Timing Receivers:
http://tf.boulder.nist.gov/general/pdf/1384.pdf

Absolute Calibration of a Geodetic Time Transfer System:
http://xenon.colorado.edu/paperIrevise2.pdf
--
Bill Byrom N5BB


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and follow the instructions there.

Re: [time-nuts] GPS Antenna Feed Line Decision

[Bill Hawkins]

My HP conical antennas had N connectors, so I used 50 feet of RG-8.
Z3801 receivers never had a problem.

RG-8 is a sturdy cable, which may be the primary consideration for a 38
foot drop unsupported through the mast.

Don't have any comparison to lighter cable, though.

Bill Hawkins
 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Clay
Autery
Sent: Saturday, September 02, 2017 1:57 PM
To: Time Nuts
Subject: [time-nuts] GPS Antenna Feed Line Decision

Having decision-making problems for the materials for my GPS main
feedline.  Going to use a TM LMR stock, just can't decide how big to go
with it...

26 dB 5vdc antenna on top of a 38 foot mast.  Feed will come down the
inside/center of mast and exit near the bottom, thence routed through a
window and to the GPS distro amp. Antenna will feed GPSDO, NTP Server,
Blitzortung System Blue station, and one other device TBD.

Just cannot decide how big to go with the antenna to distro amp feed...
Assuming 50 feet total (38' mast + 12 feet to amp in shack) @ 1800 MHz
(closest to 1725 MHz), here are the losses from just this piece
(ignoring the amp to device jumpers):

-240 = 5.45 dB XXX - too much loss?
-400 = 2.85 dB
-500 = 2.30 dB  XXX - too hard to find
-600 = 1.85 dB
-900 = 1.25 dB

Money not necessarily a consideration as this is a short run for a
permanent installation.  Don't anticipate ever moving the GPS antenna to
the tower.
For 900 and likely 600, likely would not be able to do it in one piece
as routing it out of the mast and into the shack would get complicated.
Would likely bring it out of the mast at the bottom with a right angle
connector, and then use a smaller diameter jumper for the last 12 feet.
500 is pretty uncommon stock wise and it and connectors are harder to
find.

I already have the tooling for both 240 and 400... but I definitely
don't want to challenge ANY of the devices for signal gain.

So it mostly boils down to easy vs. more effort ($$ aside)  Is it
worth the additional trouble to move from -400 to -600 or -900?  To NOT
lose the 1-1.6 dB additional?

I'd appreciate your recommendation and reasoning. Thanks in advance!

73,

--
__
Clay Autery, KY5G
MONTAC Enterprises
(318) 518-1389

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Re: [time-nuts] How well does GPS work in the Arcitic?

[Bill Beam]

On Mon, 14 Aug 2017 18:19:56 -0700, jimlux wrote:

>On 8/14/17 5:58 PM, Bill Beam wrote:
>> GPS orbit inclination is 50-60deg.

>55 degrees

Current TLE show I= low of 51.7 to I= high of 56.6.


>> At my latitude of 65N satellites are about 15deg above the horizon to the 
>> north.

>That would be for satellites that are "over the pole" with respect to you?


yes

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Bill Beam
NL7F



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Re: [time-nuts] How well does GPS work in the Arcitic?

[Bill Beam]

GPS orbit inclination is 50-60deg.
At my latitude of 65N satellites are about 15deg above the horizon to the north.
Regards.

On Mon, 14 Aug 2017 16:45:22 -0700, Hal Murray wrote:


>The satellite orbits only go so far north?  If you are far enough north for 
>that to be a problem, can you pick up the satellites across the pole?

>I have several days of NMEA log files from 68 N.  I think it will be simple 
>after I have done it, but it may be a while before I get time to plot them.  
>Does anybody have (non-Windows) code to that?



>-- 
>These are my opinions.  I hate spam.



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Bill Beam
NL7F



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Re: [time-nuts] Ships fooled in GPS spoofing attack suggest Russian cyberweapon

[Bill Byrom]

This has been an area of interest to the US Air Force for many years:

http://www.ainonline.com/aviation-news/aviation-international-news/2006-10-18/usaf-facility-tests-gps-jamming-vulnerability

--
Bill Byrom N5BB

On Mon, Aug 14, 2017, at 12:46 AM, Clint Jay wrote:
> Didn't someone demonstrate this using some rather expensive but 'off the
> shelf' Rohde & Schwarz lab gear a year or so ago?
> 
> 
> 
> On 12 August 2017 at 22:23, John Allen <j...@pcsupportsolutions.com>
> wrote:
> 
> > FYI, John K1AE
> >
> > -Original Message-
> > From: YCCC [mailto:yccc-boun...@contesting.com] On Behalf Of ROBERT
> > DOHERTY
> > Sent: Saturday, August 12, 2017 9:26 AM
> > To: YCCC Reflector
> > Subject: [YCCC] Fwd: Re: [Radio Officers, ] Ships fooled in GPS spoofing
> > attack suggest Russian cyberweapon
> >
> > As if there were not enough problems in the world .
> >
> > Whitey  K1VV
> >
> > > Date: August 12, 2017 at 7:37 AM
> > > Subject: Re: [Radio Officers, ] Ships fooled in GPS spoofing
> > attack suggest Russian cyberweapon
> > >
> > > Ships fooled in GPS spoofing attack suggest Russian cyberweapon
> > >
> > > News from: New Scientis (article reported by R/O Luca Milone –
> > IZ7GEG)
> > >
> > > https://www.newscientist.com/article/2143499-ships-fooled-
> > in-gps-spoofing-attack-suggest-russian-cyberweapon/#.
> > WY6zNfZq1VA.google_plusone_share https://www.newscientist.com/
> > article/2143499-ships-fooled-in-gps-spoofing-attack-
> > suggest-russian-cyberweapon/#.WY6zNfZq1VA.google_plusone_share
> > >
> > >
> > > On date: 10 August 2017
> > >
> > > By David Hambling
> > >
> > >
> > > Reports of satellite navigation problems in the Black Sea suggest
> > that Russia may be testing a new system for spoofing GPS, New Scientist has
> > learned. This could be the first hint of a new form of electronic warfare
> > available to everyone from rogue nation states to petty criminals.
> > >
> > >
> > > On 22 June, the US Maritime Administration filed a seemingly bland
> > incident report. The master of a ship off the Russian port of Novorossiysk
> > had discovered his GPS put him in the wrong spot – more than 32 kilometres
> > inland, at Gelendzhik Airport.
> > >
> > >
> > > After checking the navigation equipment was working properly, the
> > captain contacted other nearby ships. Their AIS traces – signals from the
> > automatic identification system used to track vessels – placed them all at
> > the same airport. At least 20 ships were affected
> > http://maritime-executive.com/editorials/mass-gps-spoofing-
> > attack-in-black-sea .
> > >
> > >
> > > While the incident is not yet confirmed, experts think this is the
> > first documented use of GPS misdirection – https://www.marad.dot.gov/
> > msci/alert/2017/2017-005a-gps-interference-black-sea/  a spoofing attack
> > that has long been warned of but never been seen in the wild.
> > >
> > >
> > > Until now, the biggest worry for GPS has been it can be jammed
> > https://www.newscientist.com/article/dn20202-gps-chaos-how-
> > a-30-box-can-jam-your-life/  by masking the GPS satellite signal with
> > noise. While this can cause chaos, it is also easy to detect. GPS receivers
> > sound an alarm when they lose the signal due to jamming. Spoofing is more
> > insidious: a false signal from a ground station simply confuses a satellite
> > receiver. “Jamming just causes the receiver to die, spoofing causes the
> > receiver to lie,” says consultant David Last
> > http://www.professordavidlast.co.uk/ , former president of the UK’s Royal
> > Institute of Navigation.
> > >
> > >
> > > Todd Humphreys http://www.ae.utexas.edu/faculty/faculty-directory/
> > humphreys , of the University of Texas at Austin, has been warning of the
> > coming danger of GPS spoofing for many years. In 2013, he showed how a
> > superyacht with state-of-the-art navigation could be lured off-course by
> > GPS spoofing. “The receiver’s behaviour in the Black Sea incident was much
> > like during the controlled attacks http://onlinelibrary.wiley.
> > com/doi/10.1002/navi.183/full  my team conducted,” says Humphreys.
> > >
> > >
> > > Humphreys thinks this is Russia experimenting with a new form of
> > electronic warfare. Over the past year, GPS spoofing has been causing chaos
> > for the receivers on phone apps 

Re: [time-nuts] interesting HP divider and clock on ebay

[Bill Hawkins]

You don't have to use the long link. Just search eBay for item
#232426132876.

It's pricey because it is from one of those resellers of surplus
laboratory equipment. Who was that outfit in Texas?

The front picture reveals that the desiccant is saturated (indicator is
pink). Rear view shows blackened silver BNC connectors. These suggest
that the instrument hasn't been reconditioned to merit that price. OTOH
it could be R@@RE.

Owned a 113B a few years ago. The 1 KC stepping motor does scream. Doubt
that there's a motor in the 115.

Would be interested in a repairable unit to measure my declining years -
not for resale.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jeremy
Nichols
Sent: Wednesday, August 09, 2017 8:12 PM

Definitely spendy. Is the 115 as noisy as the 113 (similar but w/analog
clock)? Wonder what *les douanes* would charge to get that back into
USA?
Could you claim an exemption because it was Made in USA?

Jeremy


On Wed, Aug 9, 2017 at 5:32 PM Tom Van Baak <t...@leapsecond.com> wrote:

> > Boy I have to say the front looks great. Good pixs to look at.
> > Price not exciting at all. But maybe someone has a spare kilo-buck.
>
> Paul,
>
> More info on the hp 115:
>
> http://hpmemoryproject.org/wb_pages/wall_b_page_01.htm
>
> /tvb
> ___

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[time-nuts] SOPHOS discussion of GPS jamming and eLoran

[Bill Hawkins]

SOPHOS is a European anti-malware company that publishes a daily
newsletter of oddities in the security world.
This article on jamming of S Korean GPS by N Korea may be of some
interest.

https://nakedsecurity.sophos.com/2017/08/07/cyberattacks-on-gps-leave-sh
ips-sailing-in-dangerous-waters/?utm_source=Naked+Security+-+Sophos+List
_campaign=f2c7691392-naked%252Bsecurity_medium=email_term=0_
31623bb782-f2c7691392-455148921

My apologies for the long link. You could try Googling the subject if
the link is broken up by your mailer.

Bill Hawkins

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Re: [time-nuts] A milestone approaches

[Bill Riches]

Hi Tom

I passed this along to two of my old time computer gurus - I am sure they will 
want to celebrate!!

73,

Bill, WA2DVU
Cape May

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak
Sent: Wednesday, July 12, 2017 8:19 AM
To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
Subject: Re: [time-nuts] A milestone approaches

Hi Bill,

> Got this from a friend whose MN license plate is UNIX.

Join the club! There's ~50 of us in the US: http://leapsecond.com/pages/unix/


> At that instant, billions of Linux and Unix computers and devices

Plus embedded devices, such as Arduino, where 31-bit time_t C libraries are 
also used...


> return time() == 15.  It will not be until 2033 when that number 
> reaches 2 Billion.

Thanks for the notice. Add these to your list:

1414213562 0x544b2fba Sat Oct 25 06:06:02 2014 GMT (sqrt 2)
1415926535 0x54655307 Fri Nov 14 00:55:35 2014 GMT (pi)
1420405752 0x54a9abf8 Sun Jan 04 21:09:12 2015 GMT (H-maser Hz)
15 0x59682f00 Fri Jul 14 03:40:00 2017 GMT (1.5 billion)
1616161616 0x6054ab50 Fri Mar 19 13:46:56 2021 GMT (pretty in dec)
1616928864 0x60606060 Sun Mar 28 10:54:24 2021 GMT (pretty in hex)
1717171717 0x6659f605 Fri May 31 17:08:37 2024 GMT (dec looking like oct)
1886417008 0x70707070 Thu Oct 11 13:43:28 2029 GMT (pretty in hex)
1985229328 0x76543210 Sun Nov 28 04:35:28 2032 GMT (hex digit countdown)
20 0x77359400 Wed May 18 04:33:20 2033 GMT (2 billion)
2004318071 0x Thu Jul 07 04:01:11 2033 GMT (pretty in hex)
2147483647 0x7fff Tue Jan 19 03:14:07 2038 GMT (end of time)
2147483648 0x8000 Tue Jan 19 03:14:08 2038 GMT (you survived)

While we're at it, we have a rare T MJD event coming in 2023:

1968-05-24 00:00:00 UTC (DOY = 145, Fri) = JD 244.5 = MJD 4.0
1995-10-10 00:00:00 UTC (DOY = 283, Tue) = JD 245.5 = MJD 5.0
2023-02-25 00:00:00 UTC (DOY =  56, Sat) = JD 246.5 = MJD 6.0

/tvb

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[time-nuts] A milestone approaches

[Bill Hawkins]

Got this from a friend whose MN license plate is UNIX.

Begin copy of note

I'm curious if your friends on the time wizards mailing list have
noticed that an important moment in computer history approaches.

On Thursday night, 21:40 PM CST, it will be exactly 1.5 billion seconds
since Jan 1, 1970 UT, the Unix EPOCH.  At that instant, billions of
Linux and Unix computers and devices, everywhere on the planet, will all
return time() == 15.  It will not be until 2033 when that number
reaches 2 Billion.  The Thursday date is computed as follows:

% cat >epoch.c
#include 
#include 
#include 

int main(int argc, char **argv) {
const time_t gsec = 1.5e9;
struct tm thursday = *localtime();
char buf[100];

strftime(buf, sizeof(buf), "%m/%d/%y %H:%M:%S", );
printf("Epoch + 1.5B seconds = %s\n", buf);
return 0;
}
% gcc -Wall epoch.c
% ./a.out
Epoch + 1.5B seconds = 07/13/17 21:40:00
%

And if they haven't noticed, it might be a good time to point it out.

End copy of note

Some of us are impressed by long strings of zeros, so here I am,
pointing it out.

Bill Hawkins

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Re: [time-nuts] Anderson PowerPole (was Charles Wenzel GPSDO)

[Bill Byrom]

Since I have met Charles in person a couple of times at his office in
Austin and used their microwave multiplied golden low phase noise
oscillators for a project and recommended Wenzel to others, I admit my
bias in favor of his projects.

I was going to comment earlier in this thread about the advantages of
Powerpole connectors and my bad experiences with old circular pin power
connectors from Molex and Amp, but decided to wait until the inevitable
storm of competing arguments blew over. I just finished wiring a
Powerpole connector to an Amplifier Research 144 MHz low noise preamp
tomorrow for use in Field Day this weekend for some satellite contacts
by a friend. He's also borrowing a big 100 AH 12V AGM battery from me,
so I added an inline fuseholder to a Powerpole standard ARES red/black
plug setup.

We should all remember that circuit protection, a proper fire
extinguisher, and safety goggles are important for fire and personal
(explosion) safety when initially connecting our new experimental
setups. Fuses or circuit breakers should always be used for connections
to batteries. Even small modern batteries can supply very high peak
currents, and in some cases you might not be there to handle the
emergency. My two personal stories are:

(1) A common 9V (NEDA1604 style) battery should never be left where it
might contact a metal short, and should never be left in a pocket. I
knew better, but temporarily slipped an alkaline 9V battery into a
trouser pocket, where it was shorted by my keys and became extremely hot
very rapidly. The peak current might reach 10 A (depending on the
battery chemistry and how it's shorted), so the battery heats up very
rapidly!

(2) When I was in high school (about 45 years ago) and still learning
how electrical and electronic stuff worked, I decided I needed to try
resistance soldering. This soldering technique was described in the
William Orr W6SAI Radio Handbook (unrelated to the ARRL  Handbook).  I
had some AWG 14 insulated wire and a surplus 2.5 V filament transformer
(rated for over 25 Amps, I'm sure). I found some old welding rods or
copper rods to apply the current to the joint being soldered. After
hooking it all up, I applied the rods to the joint and was surprised
when the copper wire used for my connections rapidly turned red hot and
fused, dropping molten copper onto the floor. I thought I understood
Ohm's Law and power dissipation in resistors, but obviously I didn't
have a practical understanding of the current handling capacity of the
wire. The wire acted as a fuse before the primary circuit fuse or mains
circuit breaker had a chance to trip.
--
Bill Byrom N5BB

- Original message -
From: Chris Albertson <albertson.ch...@gmail.com>
...
I did something stupid last might and assembled power distribution not
as designed with a mosfet switch and diode in backwards then connected
a high power density battery.  I had an open flame along an entire run
of #18 cable but finally the coper conductor failed (the metal
vaporized) and the circuit opened and the flame stopped.   I have some
chared remains of wires and crunchy black melted plastic.  But the
XT60 connectors are still good.  The metal parts inside are still
shiny gold plated and the nylon shells are good as new, after cleaning
the soot off.

I was actually holding the connecter in my hand when the thing went
off like a bomb, but just minor burns.  Still amazed the connecter is
fine after unsoldering the little stubs of burned wire from the pins.



On Thu, Jun 22, 2017 at 12:19 AM, Tom Van Baak <t...@leapsecond.com>
wrote:
> Wes, Don,
>
> I am quite surprised at the negative reaction to Anderson Power Pole 
> connectors. I have found them the best DC connector out there. I have used 
> them for a decade or two for all my DC feeds and have never had a problem: in 
> my home lab, my car, even for my laptop charger. They are inexpensive, 
> reliable, genderless (hermaphroditic) and easy to crimp. I use them for my 
> 5V, 12V, 24V, and 48V supplies as well as my DC backup systems.
>
> What on earth are you doing with them that causes them to disconnect? I mean, 
> they are not meant for towing or lifting or rappelling. For critical 
> applications there is a plastic gizmo that keeps them mated; or just use a 
> square or figure 8 knot on the cables.
>
> /tvb
>
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] CRT for Tracor 527A

[Bill S]

Dave,
I have a complete 527A with a slightly screwed up case (someone removed 
the handles and smoothed the edges!) that was working when I last used 
it about 6 years ago. The crt at the time was good and working. I had 
planned to put it on ebay but never got around to it. Email me off list 
if you're interested.

On 6/20/2017 5:01 PM, David C. Partridge wrote:

Trying a long shot here, I'm looking for a 1" CRT type 1EP1 (or 1EP11, or?)
for a Tracor 527A Frequency Difference Meter.
  
I did spot some on eBay but the vendor had a rather high opinion of their

worth :) at over 300 dollars

Anyone got one to spare?

Thanks
Dave

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[time-nuts] The clocks at Windsor Castle, UK

[Bill Hawkins]

Happened to watch a PBS/BBC program called "Queen's Castle" episode 102
- Four Seasons, that was filmed in 2005 at Windsor, not Buckingham.

One of the segments was about the castle timekeeper, Steve Davison. He's
responsible for 450 clocks, some 300 years old. His biggest challenge is
the end of British Summer Time, when each clock must be advanced 11
hours, stopping until striking finishes. Old clocks were not designed
for Fall Back. Takes him 16 hours.

There was a brief shot of his workshop, with a clock repair in progress.
No sign of a time standard. No discussion of leap seconds, either.

Tried to find him, but only found a 2013 ad for a time keeper to
maintain 1000 clocks in various castles.

Hope that wasn't too far off topic.

Bill Hawkins

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Re: [time-nuts] Powering up a long inactive 5061A

[Bill Hawkins]

The first thing you should do is to check the condition of the power
fuse. If it is blown or missing, you have some work to do looking for
the cause of the fuse trouble.

If you are concerned about old electrolytics in the power supply, and
you can't check them for capacitance when off, there is an alternative
to using a Variac.

Cut one wire of an extension cord in order to put a lamp socket in
series with the load. If line power is 120 volts, put a 100 watt bulb in
the socket. Turn on the unit and be ready to turn it off again if the
bulb lights at near or full brilliance. If it does, you have the same
work to do as if the fuse had blown. If it starts bright and dims, you
may be forming electrolytics.

If the bulb maintains the same brightness, try a bigger bulb - or
disconnect the ovens.

You definitely need to read the part about running the ion pump.

Bill Hawkins

Disclaimer: I haven't tried this on an HP5061. You could still damage
the switchers. You can't detect open capacitors this way.


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hugh
Blemings
Sent: Thursday, June 15, 2017 1:02 AM

My intuition is to set it to one side until I can become familiar with
the operating manual and potentially bring power up to it slowly with a
Variac or similar.


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Re: [time-nuts] Two pieces of old General Radio Freq. Nuts

[Bill Byrom]

Yes, the GR-874 was used on a number of Tektronix products introduced in
the 1960's and 1970's.

https://en.wikipedia.org/wiki/GR_connector
http://w140.com/tekwiki/wiki/GR-874_connector

Both the GR-874 and APC-7 connectors are sexless, and any connector can
mate with any other.
--
Bill Byrom N5BB

- Original message -
From: Gary Woods <garygar...@earthlink.net>
To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Subject: Re: [time-nuts] Two pieces of old General Radio Freq. Nuts
Date: Fri, 26 May 2017 23:21:11 -0400
...
Neat stuff...did anybody but GR use those hermaphrodite connectors?  I
have
an adapter for them that came with a wide-band amplifier; "delay line"
type, with a whole row of, I think, 6AK5s in it.

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Re: [time-nuts] Lady Heather and Lucent RFTGm-II-XO / RFTGm-II-Rb

[Bill Hawkins]

Been there and done that. Used a PicoScope in serial decoding mode to
get the bytes by clipping a probe to one of the serial lines. Got the
manual for the Motorola receiver from a web search, found the messages
detailed therein. Did this several years ago and those memories have
been overwritten. Still have the files, though. Only found Motorola
messages, nothing generated by Lucent code. Lucent uses the Motorola
messages to control the state of the units.

Still have the RFTG assembly with power supply, if there's any interest.
Seemed to me the group didn't think it was a fine instrument, but it is
well built. Have moved to an old folks home and found other projects to
keep me occupied. Make me an offer that might motivate me to pack and
ship it, with the data I collected.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark
Sims
Sent: Thursday, May 25, 2017 5:53 PM

I have my RFTG connected and have the Lucent software talking to it.  I
also have a (crappy) serial port monitor program (Microsoft portmon)
running and sniffing the traffic.   It appears that the control requests
and responses are in what amounts to TSIP format.   No idea yet what the
contents of those messages are... or how much of it can be figured
out...

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Re: [time-nuts] NOOB Q re LH

[Bill Hawkins]

Many years ago, an acquaintance tried to sell me his Ercoupe airplane.
We went up for a test drive. He gave me the yoke and began pointing out
the meaning of all the gauges. I looked up from that and saw that we
weren't horizontal. I experienced information overload for the first
time, and decided that I wasn't meant to fly small aircraft.
 
I get the same feeling looking at the Lady Heather screens that have
appeared in this list. There is an information density that begs for a
VR display, and even then it would take more years than I've got left to
become comfortable with it.

This is no criticism of Mark Sim's work. It tells you all you ought to
know. I just have trouble assimilating it.

Good luck.

Bill Hawkins


-Original Message-
From: Frank Howell
Sent: Monday, May 22, 2017 4:05 PM

Hi Folks,

Great list...I'm learning a lot. Could I trouble you for suggested
readings on the display content and interpretation from Lady Heather?

Yes, I've read the PDF and the lines of codeand studied the websites
of leapsecond.com, KO4BB.com, and the Dec 2014 thread on the time-nuts
archive which basically asked this same Q. Any updates to that answer
which was basicallyread a bunch of stuff and figure it out? I can do
that but thought I'd politely as the listserv once again.


73, Frank K4FMH

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Re: [time-nuts] Looking for info on Trimble 16634-10

[Bill Hawkins]

FWIW, that looks like aviation equipment (gov't or civil), with a
locking connector.

That stuff is designed for minimum size and weight. You might find the
inside of the box quite cramped.

Buying aviation parts is even more expensive than buying boat parts.

Bill Hawkins


-Original Message-
From: time-nuts on behalf Of Bob Bownes
Sent: Friday, May 19, 2017 10:48 PM

Pretty sure that connector is an off the shelf Amphenol part. If you
can't find it, however, you can replace it with an off the shelf one
that will fit in the same hole. (If your lucky, you can even re-use the
pins.)

The replacement will run you about $30-40 for the pair, chassis and
plug. Check Mouser, etc. 

> On May 19, 2017, at 23:21, Bob kb8tq <kb...@n1k.org> wrote:
> 
> The mating side of that 22 pin connector isn't going to be cheap. It 
> looks like something out of their government systems group back in the
late 90's. If it is, you may have a hard time getting info on it.
> I'd pop it open and see what's inside. At least that will give you an 
> idea if it's 20 years old or 5 years old. Knowing the era should help
in the search for information.
> 
> Bob
> 
>> On May 19, 2017, at 10:21 PM, Scott Armstrong <aa...@vntx.net> wrote:
>> 
>> I acquired a Trimble 16634-10 receiver. A search of the web has 
>> turned up nothing so far.
>> The unit is in a steel box built like a tank. SMA connector for 
>> antenna input and a 22 pin circular connector for the I/O and power
>> 

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Re: [time-nuts] Machining some aluminum help!

[Bill Hawkins]

These threads where there is not enough information to define the
problem can grow forever, because they are based on speculation, not
facts.

Corby, you have decided what you need based on what you know, but the
rest of us need a more general statement of the problem.

Unless, of course, that is something you do not choose to reveal.

Bill Hawkins


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Re: [time-nuts] time.gov reply from NIST

[Bill Byrom]

Thanks for this post, Jerry. Could you please forward my post to Andrew?
As you can see below, I have some issues about the widget I want to
discuss with him, and I don't have his email address. I visit NIST
Boulder every couple of months for business, but I'm never meeting with
people in his group.

I noticed unusual errors (of up to about 1 second) when the thread first
appeared here, and also noticed different errors when using the NIST
widget on my personal website. But tonight (as I'm posting), I'm
listening to 5 MHz WWV from the Dallas TX area and see no visible error
(within my human ability) comparing listening on an AM receiver to WWV
while watching these websites:

(1) http://nist.time.gov/
(2) http://time.gov/widget/widget.html  
(3) http://time.gov/widget/ 

All three of these URL's work on most desktop browsers. The first two
don't need Flash, but (3) uses Flash. So (3) won't work on a mobile
Apple device which doesn't support Flash (such as an iOS device such as
an iPad, iPod, or iPhone).

In August 2011 (which I believe was shortly after the (3) Flash widget
was first published), I found a bug in the (3) Flash widget which
prevented the display between 12:00:00 AM and 12:59:50 AM (or 00:00:00
and 00:59:00 in 24-hr mode). The display instead showed PM (in 12-hr
mode) during that interval. I have an email I sent myself about this bug
but I can't find any email traffic to or from NIST at that time. It was
fixed long ago, so they may have fixed it without my complaint or I
might have spoken to them on the telephone.

I find that the Flash widget (3) works fine when the code is placed on
my website, but instructions are not available to do this for the
non-Flash (2) widget. I wish NIST would update the (2) non-Flash widget
so that it could be easily installed on another website. If anyone knows
how to do this, please let me know! I'm hoping Andrew can assist me.
--
Bill Byrom N5BB

- Original message -
From: Jerry Hancock <je...@hanler.com>
To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Subject: [time-nuts] time.gov reply from NIST
Date: Fri, 12 May 2017 17:45:45 -0700

Sounds like there was a change made to the time.gov code recently that
could have caused the error we noticed.  I replied to Andrew that I
didn’t remember the time.gov site loading any slower or faster than
usual.


Jerry, 

Thanks for writing.  I have had a few reports of incorrect time, but
they were from people comparing to cell phones and WWVB clocks.  I have
not been able to replicate any errors, but I had our network folks
verify that the servers serving the web content are synchronizing with
NTPd to NIST servers.  I trust time-nuts implicitly - if you guys say
there's a problem, I believe it.

It would be difficult to believe that the server clocks could be on that
far, and then corrected, and then off again.  If a refresh fixes it,
then I'm confident that it is a network problem. The app corrects for
half the round-trip delay, assuming that to be a good estimate for the
one way delay from the web server.  However, if there is a network
bottleneck or vary slow packet transfer in one direction, then the
correction will not be accurate.  Have you happened to notice if it
looked like it took several seconds to connect after making the web
request?

I might have to take out the correction and just report the delay, how
it used to be.  This is also how the widget operates:
http://time.gov/widget/widget.html <http://time.gov/widget/widget.html> 
So a check of the widget at the time the HTML5 application is showing an
error I would expect it to be correct.  

Thanks for the information!  Please keep in touch.

Andrew Novick
NIST
(xxx) xxx -  phone removed by Jerry

On 5/12/2017 11:15 AM, Jerry Hancock wrote:
> Hello,
> 
> I am a member of a group of individuals called time-nuts.  Most of us have 
> atomic clocks or at a minimum, GPS disciplined oscillators that record and 
> display time with a variance below 10 nanoseconds.  Yesterday around 14:00 
> Pacific Time I noticed while setting a new watch that time.gov 
> <http://time.gov/> was as much as 5 seconds slow.  After reporting this on 
> the time-nuts site, other members found the same discrepancy.  This was 
> corrected later in the day.  At least one member of our group reported that 
> refreshing the site corrected the error.  I found that by running the flash 
> application that also corrected the error.  Since around 18:00 Pacific 
> yesterday the error has been corrected.
> 
> Can you account for the discrepancy?  
> 
> Thank you,
> 
> Jerry Hancock
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Re: [time-nuts] HP10811 Oscillator Thermal Fuse

[Bill Hawkins]

Labs could have used a common gas heater for the crystal ovens, with a
bit of rewiring.

No fire hazard there - you've got a chimney. Also, flame safety is well
developed for gas heaters.

Would have required throttling gas flow control.

Bill Hawkins

Another possibility is circulating hot water.

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
kb8tq
Sent: Thursday, May 11, 2017 6:25 AM


Ultimately it all came to no good. The energy conservation rules simply
took over. Shutting down everything during off hours became the way a
lot of outfits did things. Don't turn off all your bench gear and you
get a nasty note. I am not aware of full power being dropped during off
hours. That tends to take out things you really do not want to shut down
(fire sensors .). 


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Re: [time-nuts] Using 5335 frequency counter for timing

[Bill Byrom]

First I should disclose that I work for Tektronix, and have done so for
30 years. So I have worked directly with many generations of
oscilloscopes. Good oscilloscopes can make timing measurements of up to
about a millisecond with timing errors of 10's of nanoseconds.

There are a very large range of oscilloscopes using different
technologies over the past few decades, so there are several different
answers to your questions. The range of bandwidths and new instrument
prices range over a factor of roughly 1,000. Bandwidths range from about
30 MHz to 70 GHz, and prices from a few hundred dollars to a few hundred
thousand dollars US.

Many high-end scopes do have external clock inputs (usually 10 MHz), but
this feature is not usually available on lower end or older
oscilloscopes. This only affects the accuracy of longer time interval
measurements (over 1 us), where the internal clock error is usually not
any better than 1 ppm (and 50 ppm for low cost oscilloscopes). Internal
timebase error for a 1 second measurement interval is in the several
10's of ppm for most low-end to mid-range oscilloscopes.

Short-term time measurement error for high-end oscilloscopes can be
under 1 ps, and in equivalent time mode is limited by trigger and
aperture jitter. Lower cost oscilloscopes might have short term timing
errors of several ns, limited by jitter and risetime (bandwidth).

Analog oscilloscopes have analog timebases which have large errors
compared to digital oscilloscopes. They have been obsolete for about
20-25 years.

There are several digital oscilloscope technologies. 
*  The easiest to understand is real time sampling, where you have a
sampler running at a high sampling rate and each sample is converted in
to a digital value in real time. A single trigger event results in a
waveform capture, but the instrument can capture a waveform without a
trigger event. The memory length can be large (1 G sample in some
cases), but the sampling rate is limited by the need for the A/D to
complete the conversion in real time. Using internal A/D interleaving,
waveform sampling rates up to 200 GS/s are available, but the cost is
very high in such cases. Lower cost recent models typically have
sampling rates of 1 to 5 GS/s.
*  Many (but not all) real time oscilloscopes also offer random
equivalent time sampling. In this case the instrument samples at a much
lower sampling rate than would be required for the chosen time/division
setting and waveform length. So, for example, every 10th waveform point
might be filled after each trigger. In this mode, the signal has to
trigger the instrument multiple times (in some cases thousands of
trigger events) before all of the waveform record points are filled. The
sample points are purposely randomly delayed at the start of each
sub-acquisition cycle and the displayed points appropriately skewed so
that all waveform samples are filled without aliasing. This gives you
much better time resolution than with real time sampling, but the
trigger must be extremely accurate and the signal being measured must
have low jitter. Unless you want to get an eye pattern, the signal must
be repetitive (same exact waveform on each trigger). A trigger is
required for this mode to build up a waveform.
*  Sequential sampling oscilloscopes: These instruments are often
referred to as "sampling scopes", although this is now a misnomer since
all digital (and some analog) oscilloscopes use a sampler. This is a
sequential form or equivalent time sampling, and only one sample (or
less) is acquired for each trigger event. So a 1,000 point waveform
requires that 1,000 triggers must be accepted, and since the trigger
processing rate is usually on the order of 200 k/sec only about 1/1000
of the trigger events are actually used if the trigger signal is 200
MHz. An external separate trigger input is usually required. This
instrument has the highest time resolution and short-term timing
accuracy and vertical accuracy of any oscilloscope type, but must be
used for stable repetitive signals.

The waveform update rate of equivalent time mode (repetitive or
sequential) is much slower than real time mode due to the many waveforms
which must be acquired in equivalent time mode to build up a waveform
record. 
--
Bill Byrom N5BB
Tektronix RF Application Engineer

- Original message -
From: Hal Murray <hmur...@megapathdsl.net>
To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Cc: hmur...@megapathdsl.net
Subject: Re: [time-nuts] Using 5335 frequency counter for timing
Date: Sun, 07 May 2017 20:11:58 -0700


kb...@n1k.org said:
> None of them will do as well as a really fast scope.

How accurate is the clock in a scope?  Do the high end scopes have an 
external clock input?

I remember playing with a scope many years ago.  Trigger on a PPS from a
GPS, 
look at the next PPS.  It should be 1 second later.  I think the scope I
was 
using was off by 6 PPM.

I'd expect that t

[time-nuts] XL microwave model 3401

[Bill]

Hi,

I am looking for a service manual for XL Microwave Model 3401 Frequency Counter.
Please advise if you have one for sale or one I could dowmload.

Bill Reed

br...@otelco.net


---
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[time-nuts] Email address change

[Bill Riches]

As you have heard Verizon is canceling their email address operation.  I
don't know when but it will be soon.  My new email address will be

 

bill.ric...@gmail.com <mailto:bill.ric...@gmail.com> 

 

Please correct your address book.

 

Thank you.

 

Bill Riches, WA2DVU 

dB Electronics

Cape May Court House, NJ 08210

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Re: [time-nuts] Austron/ Systrom Donner 8181 Time Code Reader

[Bill Hawkins]

There is usually a power dissipation reason why a resistor becomes
toast, and the reason is frequently a shorted bypass cap or a shorted
device.

Have you measured the resistance to ground of the end of the resistor
opposite the power supply?

Sometimes inputs get high voltages and short the amplifying device.

Sometimes that is reason the units were for sale.

Hope I'm wrong.

Bill Hawkins
 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dave
Wood
Sent: Saturday, April 22, 2017 8:43 PM

Anyone on the list own the above Time Code Readesr.  I have one of each,
they are identical with the same issue.  I need to identify the correct
value of a resistor in the power supply that provides 27 volts to the
input amp.  They are both toast in my units and I do not have a manual.
Thanks in advance!  Dave ___

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Re: [time-nuts] uncertainty calculations

[Bill Byrom]

Below your post are posts I copied from last year from me and others
about the pseudo-random phase modulation in certain Tektronix counters
from the 1980's and 1990's. You can read more about metastability at
these links:

http://www-classes.usc.edu/engr/ee-s/552/coursematerials/ee552-G1.pdf

http://www-s.ti.com/sc/psheets/sdya006/sdya006.pdf

My main point is that averaging quantized values (contents of a counter
at the end of a gated input) doesn't always work as intended if there is
some bias in the quantization process due to metastability or other
timing nonlinearities or if  the random timing jitter is very small.
Here are some examples:

(1) Let's say that the 1 PPS signal is is generated by a process which
has NO sawtooth timing edge delay errors (jitter) due to
resynchronization. We use that signal to gate a counter which is clocked
by a 10 MHz signal with very low jitter. If the gating and counting
circuits use fast logic and they react to the rising edge of both
signals, then as long as the timing relationship between these two input
signals is stable and the rising edge of the 1 PPS signal is coincident
with the falling edge of the 10 MHz clock, there will be no
metastability and the counter will always register 10^7 counts per gate.
The system is deterministic over time intervals of many years. See
Figure 8 (on page 6) of the second link above (TI application note).

In this case, averaging has no effect. Over time intervals longer than
the lifetime of a human the count will always be 10^7.

(2) Now let's say we adjust the delay of the 10 MHz clock so the 1 PPS
rising edges coincide with 10 MHz rising edges. We now have the
metastable situation shown in Figure 2 (on page 2) of the TI application
note. We now don't know if the first clock rising edge within the gate
interval will be counted. Similarly, we don't know if the last clock
rising edge within a specific gate interval will be counted. If neither
edge is recognized the count will be 9,999,999. If one edge is
recognized the count will be 10,000,000. If both edges are recognized
the count will be 10,000,001. The system may jump between these three
cases slowly in a manner which is not completely random. So if you
average you might get the correct result (remember - we are assuming
that the frequencies and timings of the external signals are perfect),
or have an average result anywhere between -1 count and +1 count from
10,000,000.

(3) Finally, consider the case of a GPS 1 PPS output with sawtooth
timing jitter due to the manner the 1 PPS signal is generated by one
clock sampling another signal. If there is any bias in the sawtooth
delay my guess is that averaging might not produce the desired result,
especially if some process in the accumulation of the counter results
does not perform end-to-end data collection and only averages some of
the counts.

With regards to error introduced by the purposeful phase jitter imposed
on the clock: Voltage digitizing systems often add known analog dither
noise before an A/D, then remove that noise digitally from the result.
This can improve the accuracy of systems by reducing the effect of
differential nonlinearity and other system errors.
--
Bill Byrom N5BB
Full disclosure: I am a Tektronix Application Engineer

- Original message -
From: Hal Murray <hmur...@megapathdsl.net>
To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Cc: hmur...@megapathdsl.net
Subject: Re: [time-nuts] uncertainty calculations
Date: Sat, 15 Apr 2017 21:46:22 -0700

t...@radio.sent.com said:
> * You might have any possible phase relationship between the two
>   signals. If they are exactly related by a 10^7 ratio, it's possible
>   for the 1 PPS edges to exactly coincide with the 10 MHz edges.
>   Depending on the type of gating circuit, you will have jitter and
>   possibly metastability resolving whether which edge occured first. ...

> * To stay away from such problems, most precision counters add a small
>   amount of controlled jitter (phase modulation) to the clock.  ...

My experience with metastability is that it's really hard to make it
happen.

Are the clock and data in a good lab setup really stable enough to make 
metastability a problem?

How much does the added jitter screw up measurements where it isn't
needed?

-- 
These are my opinions.  I hate spam.
___




----- Original message -
From: Bill Byrom <t...@radio.sent.com>
To: time-nuts@febo.com
Subject: Re: [time-nuts] How does sawtooth compensation work?
Date: Sun, 07 Aug 2016 21:36:21 -0500

A slight correction to a typo in the description below (sorry for the
long delay). The correct Tektronix model numbers of these counters start
with DC (not TM).

The Tektronix TM500 (manual control) and TM5000 (GPIB or manual control)
instruments which used the National Semiconductor MM5837 noise generator
chip were the following:
DC509
DC510
DC500

Re: [time-nuts] uncertainty calculations

[Bill Byrom]

I believe that the problem is that the error in any one measurement is
not uniformly distributed in exactly that way. If you are trying to
count how many 10 MHz (100 ns interval) intervals occur between the 1
PPS edges in a period counter, you have to deal with the following?


* You might have any possible phase relationship between the two
  signals. If they are exactly related by a 10^7 ratio, it's possible
  for the 1 PPS edges to exactly coincide with the 10 MHz edges.
  Depending on the type of gating circuit, you will have jitter and
  possibly metastability resolving whether which edge occured first. The
  same thing happens on the end of the measured interval, but (depending
  on how it's set up) the propagation delays and metastability and
  jitter might be different. So you could get millions of sequential
  counts which were 1 count low, followed by millions of counts which
  were one count high, with no counts exactly at 10^7.


* To stay away from such problems, most precision counters add a small
  amount of controlled jitter (phase modulation) to the clock. When
  averaged over many measurements the effects of the two edges (gate and
  clock) lining up exactly are greatly reduced, since you are sliding
  one back and forth across the other with the modulation and the chance
  of metastability is small (assuming the signal being measured doesn't
  happen to match the phase modulation frequency).


* The metastability problem depends on how the edges are compared. Some
  traditional flip-flops and latches can be thought of as analog gain
  elements connected so that they tend to sit in state A or state B,
  which involve analog voltages and currents. If you graph the energy in
  the system, the energy is low in state A, rises to a peak halfway
  between A and B, and falls to a low value at state B. If the
  recognition of the timing edge occurs early enough the system remains
  in state A. If the timing is later the system is pushed toward the
  peak, but doesn't get over it and returns to state A. But if the
  timing is at the perfect location the system is balanced at the
  potential energy peak, and only random noise can push the system into
  a final state A or B over a significant length of time.


Sorry if this is considered obvious or trivial.

--

Bill Byrom N5BB







- Original message -

From: jimlux <jim...@earthlink.net>

To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
Subject: Re: [time-nuts] uncertainty calculations

Date: Fri, 14 Apr 2017 08:49:07 -0700



On 4/14/17 8:37 AM, jimlux wrote:

> If one is counting an unknown 1pps source with a counter that
> runs at 10
> MHz (e.g. the error in any one measurement is uniformly
> distributed over
> 1 ppm) and you collect 100 samples,

> is the (1 sigma) measurement uncertainty 0.1ppm * sqrt(100)/sqrt(12)

>

> (standard deviation of a uniform distribution is 1/sqrt(12) )

>

> (assuming for the moment that both sources have no underlying

> variability - we're talking about the *measurement uncertainty*)

>



Oops..

0.1 ppm * 1/sqrt(N) * 1/sqrt(12)



That is, the standard  deviation goes down as sqrt(N)

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Re: [time-nuts] TAPR TICC boxed (input protection)

[Bill Hawkins]

There are other ways that light can cause unexpected behavior.

In 1983 I worked on a process control system whose maiden installation
was in a corn processing plant, with lots of big valves and motors being
controlled. The cards that did A/D and D/A conversion of control signals
had UV erasable EPROMs for their microprocessors. There were a lot of
those cards.

One day the plant operators began complaining about the equipment
misbehaving on a large scale. The problem went away when the guy taking
flash pictures of our equipment stopped taking pictures.

We put black tape over the UV lenses.

Ob timenuts: This system later had a pulse frequency input card that I
connected to the power line. Used the operator's trending display for
process variables to watch line frequency change over time. It also had
pulse outputs, and a little work got it to play "Daisy, Daisy" like HAL
9000 in "2001: A Space Odyssey."

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
kb8tq
Sent: Sunday, April 09, 2017 1:34 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] TAPR TICC boxed (input protection)

Hi

If anybody gets into this sort of thing in the future - There are black
/ optical blocking die coat materials out there. They are silicone based
and quite stable. 
We used a *lot* of the stuff on watch modules after it was discovered
that the watch died when exposed to a heavy dose of sunlight (right
through the LCD and into the chip . poof!!)

Bob


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Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork crystal specs

[Bill Hawkins]

Nice article in Wikipedia. Didn't see any familiar names in the
reference list, though.

Seems to me inhibition compensation is useful for compensating for the
variation in purchased crystal frequencies, but not for temperature
compensation.

Also seems to me that a watch spends 2/3 of a day at wrist temperature
and 1/3 at bedroom temperature, which varies with the seasons.

Would a ceramic capacitor crafted for a certain temperature coefficient
work? Can the fork have a crafted tempco?

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Ron
Bean
Sent: Sunday, April 09, 2017 12:05 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork
crystal specs

>In your case, the car sits in an environment that matches their test 
>setup well. In my case ?\200? not so much.

FWIW, mine drifts pretty badly. It's in an aftermarket stereo, and I
don't remember when I bought it (I moved it from my previous car).

I assume that all quartz clocks and watches these days use "inhibition
conpensation".

https://en.wikipedia.org/wiki/Quartz_clock#Inhibition_compensation


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Re: [time-nuts] Line Frequeny Stablity

[Bill Hawkins]

Perhaps I should have clarified that while the synchronous machines all
run at the same frequency, that frequency depends on the balance of
steam (or hydraulic) power to the turbines that spin the generators and
the aggregate power demand. When the power is not balanced, the
frequency of the coupled system will change, but very slowly in
proportion to the size of the network of generators.

I don't know the effects of the DC tieline inverter, which can run at
any set frequency, but any difference in frequency has to affect the
power out of or into the tie line.

As to doing the clock adjustment around quitting time at 5 PM, my
experience is different. A system that took a frequency input and showed
it as a function of time revealed that the frequency sagged during the
workday and the air conditioning day, but was increased to make up the
lost cycles during the minimum load time around 4:30 AM.

In 1955 or so, The Air Force determined that the time of minimum human
activity (and hence the maximum probability of attack) was at 4:30 in
the morning. Independent research with traffic counters revealed a sharp
dip in traffic at that time of day. Adjusting the cycle count at the
time of minimum activity also minimized the cost of making that
adjustment. Sorry, I have no recent data, but it sure feels lonely to be
up at 4:30 AM.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jeremy
Nichols
Sent: Wednesday, April 05, 2017 6:57 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Line Frequeny Stablity

A fun way to monitor the state of the grid is to watch the web site of
the Power Information Technology Laboratory <http://powerit.utk.edu> at
the University of Tennessee <http://www.utk.edu>, Their site lists in
both tabular and graphical (map) form the frequency of the grid. Most of
it is USA-based but there are a few other countries also monitored.

I have one of the monitors (in the table display page <
http://fnetpublic.utk.edu/tabledisplay.html> my monitor is #853 in the
Western Interconnection-I'm in California).

The monitors, about the size of a thick hardback book, plug into a
convenient AC line outlet, connect to your Internet router, and have a
small puck-style GPS antenna so that it knows the time and where it is.
The unit has an LCD display of date, time, line voltage, and line
frequency.
The voltage is shown to 3 decimal digits of resolution and the frequency
to four digits.

I got my monitor from the U of T after I sent them a report on my
home-made monitor's results. It's interesting to watch the frequency
wander up and down but always average very close to 60.000 Hz. They saw
I had an interest and offered me one of their toys. The only thing it
doesn't do is connect to my PC so I can monitor it long-term. I suppose
if I were clever with network stuff there'd be a way to tap into its
data stream.

Jeremy, N6WFO


On Wed, Apr 5, 2017 at 2:12 PM, Bob kb8tq <kb...@n1k.org> wrote:

> Hi
>
> Back in high school, one of the radio club members figured out that 
> the "clock adjustment" took place locally between 4:30 and 5:00 PM. 
> Needless to say, pretty much everybody spent the next week listening 
> to WWV and watching the clock's second hand go out of sync with the
beeps.
> This was back in the  late 1960's
> and the idea of a grid was a bit looser than it is today. Indeed it 
> was post 1964 so there *were* grids big enough to take out the whole 
> north east section of the US. Since we were very much in that area the

> topic of grid sync came up. Nobody ever really had a good answer to 
> that question. That included the guys who ran the local power company.
>
> Bob
>
> > On Apr 5, 2017, at 3:05 PM, Hal Murray <hmur...@megapathdsl.net>
wrote:
> >
> >
> > preilley_...@comcast.net said:
> >> When I installed power plants in the 1970's they has a special
"clock"
> that
> >> showed the cumulative error in terms of clock time.
> >
> > How big were the grids back then?
> >
> > What was the typical range of error over a day or month?
> >
> >
> >> If the generator ran a little too fast the clock would move
forward.
> As
> >> the operator observed the clock moving away from zero he would 
> >> reduce
> the
> >> plant's  power and the clock would move backward toward zero.  ...
> >
> > Does that operator control a single generator or a whole grid?
> >
> > Does having a human in the loop help the control loop stability?
> >
> >
> >
> > --
> > These are my opinions.  I hate spam.
> >
> >
> >
> > ___
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Re: [time-nuts] Line Frequeny Stablity

[Bill Hawkins]

The rotary generators in a system of connected generators are
synchronous
machines. There is no frequency difference between them, only phase
angle,
and not much of that - if the system is stable.

The ocean liner analogy is correct, as there is only one captain
directing
the ship's course. If each plant set its own power levels it would be
very
difficult to maintain stability, due to the springiness of long
transmission
lines.

A set of connected generators is controlled by regional dispatchers, who
tell their plants how much power to generate in order for the day to
average
out to 60.000 cycles per second. They count cycles instead of measuring
the
frequency. You can count cycles with a synchronous clock.

This becomes less tidy when DC tie lines are used, because inverters
have
to be adjusted to get the correct power flow.

Hope I got most of that right.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Peter
Reilley
Sent: Wednesday, April 05, 2017 7:42 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Line Frequeny Stablity

Think of it as an ocean liner trying to keep a dead straight course to
it's destination.
It weighs many tons and wind and waves may drive it off it's path but
the captain
can correct for this.   It eventually arrives at it's destination and is

only a few feet
from the dock.

The total rotating mass of all the generators in a network is many times
the mass of an
ocean liner.   The operators do their best to keep them running at the 
correct frequency.
Unexpected load changes can cause some divergence, but over time the
average is dead on.

When I installed power plants in the 1970's they has a special "clock" 
that showed the
cumulative error in terms of clock time.   The clock had two inputs, one

from the utility
power and the other from some reference, possibly WWV.   Normally the 
"clock" was
pointing up at zero and not moving.

If the generator ran a little too fast the clock would move forward.   
As the operator
observed the clock moving away from zero he would reduce the plant's
power and the
clock would move backward toward zero.   His goal was to keep the clock 
at zero and
not moving.   Thus, your bedside clock was always on time even if there 
were temporary
excursions fast or slow.

Pete.


On 4/4/2017 5:28 PM, Thomas D. Erb wrote:
> Thanks for the info.
>
>
> So that tells me how data is recorded - but not how the frequency is
kept stable ?
>
> Is the line frequency now directly tied to GPS clock - with no drift ?
>
> Thomas D. Erb
> t...@electrictime.com<mailto:t...@electrictime.com> / Electric Time 
> Company, Inc.
> Office: 508-359-4396 x 117 / Fax: 508-359-4482
> 97 West Street Medfield, MA 02052 USA

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[time-nuts] CXR Larus STS 54500 Synchronus Timing System

[Bill]

Hi ,

I have two STS 54500 systems.

System 1 consists of:

1. GPS CLOCK   ST3E/LN HLDModel 54591
2. ClOCK   STE3T/HModel 54522
3.INPUT T1 Model 54511
4. ALARM   Model 54560 
5. IMUModel 54550
6. O/P T1Model 54571
7. OUTPUT NTS  Model 54580
8. STS 54500 card rack

System 2 consists of:

1. GPS CLOCK   ST3E/LN HLDModel 54591
2  ALARM   Model 54560 
3. IMUModel 54550
4. O/P T1Model 54571
5. OUTPUT NTS  Model 54580
6. STS 54500 card rack

The card rack weigh ~ 17 Lbs with the cards ~ 1.5 lbs each.
The systems are of very good  to excellent  cosmetic condition.
I have no info on their operational condition, but from their looks, I suspect 
they work.
There are no burns, dents or cut and jumpers.

I am asking $ 470.00 for system 1 and $ 370.00 for system 2. This includes 
shipping in contentinal US. Free shipping. No foreign.
Search CXR Larus on Ebay and you will see that this is a great price. Ebay is 
asking that much for one card.
If no response in two weeks, I plan on putting on Ebay.

If you are interested, contact me offline. I can send pictures.

Bill Reed
br...@otelco.net

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Re: [time-nuts] Hunting dark matter with GPS data

[Bill Hawkins]

Before you go looking for flaws in space, read the comments to the
sciencemag article at the link.

Thomas Lee Elifritz is informative.

It's amazing what you can do with math if you make a few simplifying
assumptions.

Bill Hawkins
 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of André
Esteves
Sent: Friday, March 24, 2017 3:30 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Hunting dark matter with GPS data

People in the list may be interested in replicating the work...

Cheers,

Aife

http://www.sciencemag.org/news/2017/01/hunting-dark-matter-gps-data

Hunting dark matter with GPS data

By Adrian ChoJan. 30, 2017 , 2:30 PM

WASHINGTON, D.C.—A team of physicists has used data from GPS satellites
to hunt for dark matter, the mysterious stuff whose gravity appears to
hold galaxies together. They found no signs of a hypothetical type of
dark matter, which consists of flaws in the fabric of space called
topological defects, the researchers reported here on Saturday at a
meeting of the American Physical Society. But the physicists say they
have vastly narrowed the characteristics for how the defects—if they
exist—would interact with ordinary matter.
Their findings show how surprisingly innovative—and, in this case,
cheap—methods might be used to test new ideas of what dark matter might
be.

“It is so interesting and refreshing and exciting, and the cost is
basically zero,” says Dmitry Budker, an experimental physicist at the
Johannes Gutenberg University of Mainz in Germany, who was not involved
in the work. “It’s basically the cost of the students analyzing the
data.”

Astrophysicists think that dark matter makes up 85% of all the matter in
the universe. Yet so far they have inferred dark matter’s existence only
from its gravitational pull. For decades, many physicists have tried to
directly detect a promising candidate for particles of dark matter,
so-called weakly interacting massive particles, or WIMPs. But enthusiasm
is waning as ever-more-sensitive detectors have failed to find the
particles floating through our galaxy and passing through Earth. So many
physicists are thinking more broadly about what dark matter might be.

For example, instead of a new subatomic particle, dark matter could be
something far bigger and weirder: macroscopic faults in the vacuum of
space called topological defects. Topological defects are best explained
with an analogy to magnetic materials such as nickel. Nickel atoms act
like little magnets themselves, and below a certain temperature,
neighboring atoms tend to point in the same direction, so that their
magnetic fields reinforce one another. But that orderly alignment can
suffer defects if, for example, atoms in different regions point in
different directions. When this happens, the regions meet along a craggy
surface called a “domain wall,” which is one type of topological defect.
There can be pointlike and linelike defects, too.

A similar thing might happen in space itself. Some theories predict that
empty space is filled with a quantum field. If that field interacts with
itself, then, as the infant universe expanded and cooled, the field may
have taken on a value or “phase,” which would be a bit like the
direction in which nickel atoms point. Regions of space with different
phases would then meet at domain walls. These domain walls would have
energy and, through Einstein’s famous equivalence, E=mc2, mass. So they
would generate gravity and could be dark matter.

Now, Benjamin Roberts and Andrei Derevianko, two physicists at the
University of Nevada in Reno, and their colleagues say they have
performed the most stringent search yet for topological dark matter,
using archival data from the constellation of 31 orbiting GPS
satellites. Each satellite  carries an atomic clock and broadcasts
timing signals. Receivers on Earth use the timing information from
multiple satellites to determine how far it is from each of them and,
hence, its location.

To use those data to search for dark matter, the researchers had to
invoke another bit of speculative physics. Theory suggests that within a
topological defect, the constants of nature will change. In particular,
the passing of a topological defect should fiddle with the so-called
fine structure constant, which determines the strength of the
electromagnetic force and the precise frequency of radiation that an
atom will absorb or emit as an electron in it jumps from one quantized
energy level to another. But an atomic clock works by measuring just
such a frequency. So were a GPS satellite to pass through a topological
defect, the defect should cause the satellite’s atomic clock to skip a
beat.

One jump in one atomic clock wouldn’t be proof enough for topological
defects. So the researchers looked for a stronger signal, the wave of
time shifts that would sweep across the whole 50,000-kilometer-wide GPS
network if Earth passed through a large domain wall

Re: [time-nuts] True Time Nut Mission: NASA's Deep Space Atomic Clock (DSAC)

[Bill Byrom]

NASA's Deep Space Atomic Clock test mission is moving toward a late-2017
launch (don't all projects slip?). The DSAC was just integrated with the
spacecraft. The clock uses a ~40.5 GHz hyperfine transition of mercury
ions. This steers an ovenized crystal USO (Ultra Stable Oscillator) from
FEI with 1-100 sec stability <2e-13 and drift <1e-10/day. A GPS receiver
is also on board:
https://www.jpl.nasa.gov/news/news.php?feature=6784

NASA information about the DSAC applications at:
https://www.nasa.gov/mission_pages/tdm/clock/index.html

Expected DSAC performance (2014 paper). This paper claims an estimated
Allan Deviation of <1e-14 (perhaps 3e-15) at a one day interval when in
space:
https://www.researchgate.net/publication/260036335_Expected_Performance_of_the_Deep_Space_Atomic_Clock_Mission


Here are the latest two papers I can find (from Feb 2016):

** Deep Space Atomic Clock Technology Demonstration Mission Onboard
Navigation Analog Experiment:
https://www.researchgate.net/publication/293648952_Deep_Space_Atomic_Clock_Technology_Demonstration_Mission_Onboard_Navigation_Analog_Experiment

** Preliminary Investigation of Onboard Orbit Determination using Deep
Space Atomic Clock Based Radio Tracking:
https://www.researchgate.net/publication/293648187_Preliminary_Investigation_of_Onboard_Orbit_Determination_using_Deep_Space_Atomic_Clock_Based_Radio_Tracking

--
Bill Byrom N5BB

- Original message -
From: Gregory Beat <w...@icloud.com>
To: time-nuts@febo.com
Subject: [time-nuts] True Time Nut Mission: NASA's Deep Space Atomic
Clock (DSAC)
Date: Tue, 12 Jan 2016 17:31:26 -0600

Upcoming Event: Deep Space Atomic Clock
Jan. 14, 2016, at 7 p.m. PT (10 p.m. ET, 0300 UTC)
You can watch this event via USTREAM:  http://www.ustream.tv/NASAJPL2

Speakers: 
Todd Ely, DSAC Principal Investigator, JPL
Allen H. Farrington, DSAC Project Manager, JPL
http://www.nasa.gov/mission_pages/tdm/clock/clock_overview.html#.VpWMgK9OKK0
Atomic clocks are an integral, yet almost invisible component of modern
life. 
For space exploration, they have been the foundational frequency
standard for NASA's Deep Space Network. NASA's Deep Space Atomic Clock
(DSAC) Technology Demonstration Mission, led by the Jet Propulsion
Laboratory, has been maturing the latest Atomic Clock technologies into
a smaller package, suitable for installation on a variety of deep space
probes to enhance navigation precision and gravity science across the
solar system.

DSAC is scheduled for launch in mid-2016.  
Satellite being built by Surrey Satellite Technologies USA, Englewood,
CO


Sent from iPad Air
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Re: [time-nuts] PLL performance?

[Bill Byrom]

Hi, Scott. I rarely post here, but just noticed your post. I can open
the "PLL0.pdf" file, but the other files appears to be corrupted. Adobe
Acrobat Reader thinks it's not really a PDF file or it's corrupted. I'm
not ready to comment on the expected results yet, and would like to see
the histogram. 

Are you using phase detector 1 or 2? What are the details for your loop
filter?

--
Bill Byrom N5BB

- Original message -
From: David Scott Coburn <scot...@optonline.net>
To: time-nuts@febo.com
Subject: [time-nuts] PLL performance?
Date: Mon, 20 Mar 2017 21:07:03 -0400

Hi All,

I have built and tested a PLL circuit that will be used to generate a 1
MHz signal locked to a 0.5 HZ signal from a pendulum.  (Details
available upon request.)

The circuit is a classic 4046 generating the 1 MHz signal which is fed
into a 2e6 digital divider which outputs 0.5 Hz which is fed back to the
4046 phase comparator (PC).

I take a 1 MHz signal from an HP 107A run through another 2e6 divider to
generate a reference 0.5 Hz signal for the other 4046 PC input.

I tested this by feeding the 0.5 Hz output of the PLL into a "time-stamp
counter" board which I built to go into an HP 3582A Data Acquisition
unit.  The TSC uses the 5 MHz signal from the HP 107A to feed a
free-running 32-bit binary counter.  The 0.5 Hz input latches the count
value (on the rising edge of the signal), which is then logged.

See the attached diagram.  The PLL under test is in the red box.  (Not
sure what the policy is here for attachments?)

If all was perfect I would get a string of values of 10,000,000 counts
each, one every 2 seconds.

Over the course of one day the average reading is, in fact, 10e6, so the
PLL looks to be working over "long" time scales.

The attached histogram plot shows the actual data for the 0.5 Hz signal,
showing the distribution of deviations from 10e6 counts.  This is almost
a full day of data, about 40,000 readings.

The standard deviation for the data is about 55 counts.

The plot looks to my eye to be a nice Gaussian shape, so I assume that
the deviations are caused mainly by (white?) noise.  There does not look
to be much other structure in the shape of the data.  (Comments
welcome.)

Sorry for the long introduction, there are some questions coming!

I have looked for information on the web about others who may have done
this kind of PLL, but did not find much.

Does anyone know of any articles related to this?

If so, do you know what kind of performance they got?

What kind of statement could I make about the 'stability' of this
circuit?  Simplistically: a 'stability' of ~50 counts in 10e6 is ~5e-7?

By the way, this performance is WAY WAY beyond what I was expecting

Cheers,

Scott
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Email had 2 attachments:
+ PLL0.pdf
  22k (application/pdf)
+ histogram-utcday21613x.pdf
  58k (application/pdf)
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Re: [time-nuts] Antique precision timing device without electronics

[Bill Hawkins]

There is a power amplifier that was available at the time. It's called a
relay.
It would probably take two or three stages to get enough power to drive
the motor.
Were there any relays in the box?

Conservation of power says some must be taken from the fork to operate
the contacts.
This would reduce the Q, but only while the fork was touching the
contacts.
When the battery is switched off, amplitude would decay until the
contacts were no longer touched.
Then you'd get over a minute for it to stop.

At least, that's how it looks to this mechanical engineer.

Bill Hawkins

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bill
Hawkins
Sent: Thursday, March 16, 2017 1:05 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Antique precision timing device without
electronics

Hi Morris,

If there's no active devices (and you'd be sure to see them, not solid
state) where does the power to operate the motor come from? Is it the
same contacts that drive the fork?

It's amazing that there is high Q when contacts must be operated by the
fork.

Did it come with instructions for setting the weights at the end of the
fork tines?

Best regards,
Bill Hawkins 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris
Odell
Sent: Thursday, March 16, 2017 4:23 AM
To: time-nuts@febo.com
Subject: [time-nuts] Antique precision timing device without electronics

Hi all,

I was recently asked to resurrect this interesting device by a colleague
who collects antique scientific instruments. It's a "Chronoscope" made
by the H. Tinsley company in London in the early 20th century and used
to measure time intervals with the precision of those days. It's large
and heavy in a polished wooden case with a top deck that hinges up to
reveal the innards. 

The timing reference is a large tuning fork about 30 cm (1 foot) long
and running at 25 cps. It's normally in a glass fronted housing (removed
for the video) that includes a pair of hinged mechanical arms for
starting it. It's maintained in oscillation by an electromagnet and
contact arrangement powered from a 12V DC supply. The fork amplitude is
controlled by a rheostat - too much and the tines impact on the magnet.
The video frame rate makes the fork look slower than it actually is. I
was able to extract a signal and measure the frequency with a modern GPS
disciplined counter - it's 0.007% off its specified 25 Hz! The frequency
is too low for my HP 5372A so I was not able to easily get an idea of
stability or do an ADEV measurement. The fork has quite a high Q and
takes over a minute to stop oscillating after the power is turned off.
There's a built in higher voltage AC power supply, probably a mains
transformer, potted in beeswax in a polished wooden box inside that is
intended to
  energise a large neon strobe lamp used to adjust the fork.
Unfortunately the lamp was not with the unit and is no doubt
irreplaceable. 

The 25 Hz signal is filtered by an LC network  and used to run a
synchronous motor in the Chronoscope unit. Synchronous motors not being
self-starting, you need to tweak a knob to get it going - there's a joke
in there but I can't for the life of me think what it could be ?? The
"Contact" switch and associated socket on the back controls an
electromagnetic clutch that connects the clockwork counter mechanism to
the motor and the contact "on" time is indicated on the dials with 10 mS
resolution. 

There's not a single active device in there and after a clean and lube
it runs very nicely from a modern 12V DC plugpack. My friend is very
pleased with it and it will take pride of place in his collection. 

I'd be interested to know if any time nuts have knowledge or experience
of this lovely instrument.

A video of it is at  https://youtu.be/i5S8WS9iN_E

Enjoy!

Morris

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Re: [time-nuts] Antique precision timing device without electronics

[Bill Hawkins]

Hi Morris,

If there's no active devices (and you'd be sure to see them, not solid
state) where does the power to operate the motor come from? Is it the
same contacts that drive the fork?

It's amazing that there is high Q when contacts must be operated by the
fork.

Did it come with instructions for setting the weights at the end of the
fork tines?

Best regards,
Bill Hawkins 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris
Odell
Sent: Thursday, March 16, 2017 4:23 AM
To: time-nuts@febo.com
Subject: [time-nuts] Antique precision timing device without electronics

Hi all,

I was recently asked to resurrect this interesting device by a colleague
who collects antique scientific instruments. It's a "Chronoscope" made
by the H. Tinsley company in London in the early 20th century and used
to measure time intervals with the precision of those days. It's large
and heavy in a polished wooden case with a top deck that hinges up to
reveal the innards. 

The timing reference is a large tuning fork about 30 cm (1 foot) long
and running at 25 cps. It's normally in a glass fronted housing (removed
for the video) that includes a pair of hinged mechanical arms for
starting it. It's maintained in oscillation by an electromagnet and
contact arrangement powered from a 12V DC supply. The fork amplitude is
controlled by a rheostat - too much and the tines impact on the magnet.
The video frame rate makes the fork look slower than it actually is. I
was able to extract a signal and measure the frequency with a modern GPS
disciplined counter - it's 0.007% off its specified 25 Hz! The frequency
is too low for my HP 5372A so I was not able to easily get an idea of
stability or do an ADEV measurement. The fork has quite a high Q and
takes over a minute to stop oscillating after the power is turned off.
There's a built in higher voltage AC power supply, probably a mains
transformer, potted in beeswax in a polished wooden box inside that is
intended to
  energise a large neon strobe lamp used to adjust the fork.
Unfortunately the lamp was not with the unit and is no doubt
irreplaceable. 

The 25 Hz signal is filtered by an LC network  and used to run a
synchronous motor in the Chronoscope unit. Synchronous motors not being
self-starting, you need to tweak a knob to get it going - there's a joke
in there but I can't for the life of me think what it could be ?? The
"Contact" switch and associated socket on the back controls an
electromagnetic clutch that connects the clockwork counter mechanism to
the motor and the contact "on" time is indicated on the dials with 10 mS
resolution. 

There's not a single active device in there and after a clean and lube
it runs very nicely from a modern 12V DC plugpack. My friend is very
pleased with it and it will take pride of place in his collection. 

I'd be interested to know if any time nuts have knowledge or experience
of this lovely instrument.

A video of it is at  https://youtu.be/i5S8WS9iN_E

Enjoy!

Morris

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Re: [time-nuts] TDC-GPX2 TDC chip

[Bill Byrom]

"the large print giveth and the small print taketh away"

(Quoted from this great description of modern life:

http://www.tomwaits.com/songs/song/322/Step_Right_Up/ )



I'm not trying to be too critical, but look carefully at the datasheet
for that part:
http://ams.com/eng/content/download/951531/2270299/381482 



The "accuracy" can in no way be described as 10 ps. In high
resolution mode:
* Single shot RMS time resolution: 10 ps typical, 15 ps maximum

* Integral non-linearity: 20 ps max

* Differential non-linearity: 5 ps typ

* Channel to channel isolation: 20 ps typ, 100 ps max

* Offset error: 200 ps typ

* Offset error drift vs temperature: 1.5 ps typ, 3 ps max / K

* FWHM (full width half maximum) histogram: 20-25 ps



So if the temperature changes 6 F (3.3 C), the measurement may drift by
10 ps. The single shot absolute uncertainty due to jitter (see the
histogram) could easily be +/- 25 ps. There is no mention of long-term
drift, since that isn't a typical use of this part. It would be
interesting to put one in a simple oven and see how it drifts over a
few months.
--

Bill Byrom N5BB







- Original message -

From: Christopher Hoover <c...@murgatroid.com>

To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
Subject: [time-nuts] TDC-GPX2 TDC chip

Date: Wed, 15 Mar 2017 15:28:20 -0700



http://ams.com/eng/Products/Precision-Time-Measurement/Time-to-Digital-Converters/TDC-GPX2


Claims to have single-shot accuracy of 10 ps.

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Re: [time-nuts] advice

[Bill Byrom]

Review the theory and results in this paper:

http://science.sciencemag.org/content/329/5999/1630?variant=full-text[1]


For small height changes on the surface of Earth, a clock that is higher
by a distance ∆h runs faster by ...
The gravitational shift corresponds to a clock shift of about 1.1 ×
10−16 per meter of change in height.
--

Bill Byrom N5BB







On Tue, Feb 21, 2017, at 11:13 AM, Rhoderick Beery wrote:

> Greetings Time-Nuts!

> 

> I'm a physics theorist interested in performing an experiment
> to measure
> the gravitational time dilation beneath the surface of the
> Earth. Boulby
> Labs in the UK is 1.1 km down which would generate a time differential
> from

> the surface on the order of 1 part in 10^15 -- not much to work with!
>  




Links:

  1. 
http://science.sciencemag.org/content/329/5999/1630?variant=full-text=1_redirect_count=1=251c50aa-4576-4ddf-aa31-b39ac90299c2
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Re: [time-nuts] advice

[Bill Byrom]

This short paper was issued by NIST researchers in 2010, and it
discusses making accurate gravitational time dilation / redshift
measurements using lasers:
http://tf.boulder.nist.gov/general/pdf/2447.pdf



Quoting that paper:

> Differences in gravitational potential can be detected by comparing
> the tick rate of two clocks. For small height changes on the surface
> of Earth, a clock that is higher by a distance Δh runs faster by
> 

> Δf/fo = g Δh/c2

>
> where g ≈ 9.80 m/s2 is the local acceleration due to gravity. The
> gravitational shift corresponds to a clock shift of about 1.1 × 10−16
> per meter of change in height.


So at your laboratory depth of 1.1 km, the fractional frequency change
should be about:
1.2 x 10-13 (1.2 parts in 10^13)

--

Bill Byrom N5BB



On Tue, Feb 21, 2017, at 11:13 AM, Rhoderick Beery wrote:

> I'm a physics theorist interested in performing an experiment
> to measure
> the gravitational time dilation beneath the surface of the
> Earth. Boulby
> Labs in the UK is 1.1 km down which would generate a time differential
> fromthe surface on the order of 1 part in 10^15 -- not much to
> work with!

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Re: [time-nuts] advice

[Bill Hawkins]

In the confusion, I forgot that we are concerned with gravitational time
dilation, not time of flight.

The University of Minnesota has a lab about 2500 feet down in the Soudan
mine. The following is their brief description:

"The Soudan Underground Laboratory is a general-purpose science
facility, which provides the deep underground environment required by a
variety of sensitive experiments."

Here's a link to the Soudan page:
 https://www.physics.umn.edu/outreach/soudan/tour/ 

Why is it named Soudan? The original miners found northern Minnesota to
be extremely cold at times, so they named the town for someplace warm.

Let me know if you are seriously considering this, and I will find a
contact for you.

Bill Hawkins

-Original Message-----
From: Bill Hawkins [mailto:bill.i...@pobox.com] 
Sent: Tuesday, February 21, 2017 8:08 PM

Neutrinos? Look up the OPERA experiment that measured neutrinos going
faster than light. Turned out to be a loose optical fiber connector to a
timing instrument.

Fermi Lab has/had the MINOS experiment going 500 miles from Chicago to a
mine in northern Minnesota. The generated neutrinos go through Wisconsin
but are not noticed there, AFAIK.

Bill Hawkins (Resident of Minnesota, but not a physicist, just a BSME)


-Original Message-
From: Bob Stewart
Sent: Tuesday, February 21, 2017 1:48 PM

Hi,
Have you been in touch with Fermi-Lab?  They run a neutrino experiment
with a receiver somewhere underground in Wisconsin.  At least that's
what I recall.  I used to live next to a Physics professor who has a
minor part in the experiment.  I'm not even sure what sort of data they
collect there; whether it's time or something else.

Bob Stewart (Not a physicist) 

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Re: [time-nuts] advice

[Bill Hawkins]

Neutrinos? Look up the OPERA experiment that measured neutrinos going
faster than light. Turned out to be a loose optical fiber connector to a
timing instrument.

Fermi Lab has/had the MINOS experiment going 500 miles from Chicago to a
mine in northern Minnesota. The generated neutrinos go through Wisconsin
but are not noticed there, AFAIK.

Bill Hawkins (Resident of Minnesota, but not a physicist, just a BSME)


-Original Message-
From: Bob Stewart
Sent: Tuesday, February 21, 2017 1:48 PM

Hi,
Have you been in touch with Fermi-Lab?  They run a neutrino experiment
with a receiver somewhere underground in Wisconsin.  At least that's
what I recall.  I used to live next to a Physics professor who has a
minor part in the experiment.  I'm not even sure what sort of data they
collect there; whether it's time or something else.

Bob Stewart (Not a physicist) 

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Re: [time-nuts] HP5065A Rubidium question

[Bill Hawkins]

Well, if it was not working when you acquired it, the physics package
had probably reached the end of its life.

If it had been working recently and is not now, it might be repairable.

Others on this list know more about repairing than I.

Bill Hawkins 


-Original Message-
From: David Scott Coburn
Sent: Sunday, February 19, 2017 4:42 PM

I have an HP5065A Rubidium Frequency Standard which is not working.

All of the oven temperatures look OK.
The power supply voltages look OK.
The ~60 MHz going into the RVFS package looks OK.
The 5.000 MHz and the ~5.315 MHz signals are within a few Hz.  (The unit
is running open loop only.) The A7 AC amp looks to be working OK.
The A8 137/234 Hz signals look OK.
There is 20 VDC feeding the RVFS lamp oscillator.

But, there is no current coming from the photodiode.  (Maybe a few
picoamps of dark current, certainly not the expected ~50 microamps of
DC, and no 137/234 Hz signals).

It seems the most likely problem is that the Rb lamp is not coming on.
Maybe possible that the photodiode is faulty, or a broken wire, etc.

Any other possibilities I should check before setting off into the
innards of the RVFS package?

Thanks in advance!

Cheers,

Scott

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Re: [time-nuts] Have done some more cutting on the Cs beam tube

[Bill Dailey]

Is it possible that the higher temp keeps the tube "cooked off?"

Bill Dailey


> On Feb 19, 2017, at 12:54 PM, <cdel...@juno.com> <cdel...@juno.com> wrote:
> 
> Hi,
> 
> The tiny coil inside the beam path is the low frequency coil used for DC
> testing of the tube.
> 
> The tube shown is a standard performance tube and has no degaussing coil.
> 
> The flat windings on top of the shield are the C-field winding.
> 
> The high performance cavity is even "prettier".
> 
> You can see one at http://www.leapsecond.com/pages/cesium-tube/
> 
> Towards the bottom you can see the C-field windings in slots around the
> circumference of the cavity.
> 
> BTW in 5071A tubes there is no internal difference between the STD and
> High Performance tubes.
> 
> They just run at different temperatures! Saves having to build two
> different tubes!
> 
> Some more interesting 5071A tube info will post in a couple weeks!!! 
> 
> (Hint: Run your 5071A HiPerf tube at the Std tube temperature to extend
> life!!!???)
> 
> Cheers,
> 
> Corby
> 
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Re: [time-nuts] Vintage Frequency Measurement

[Bill Byrom]

The BC-221 was mentioned in a Time-Nuts thread from December, 2015.
Copying from my post in that old thread:

Back in the early 1970's I took my BC-221 and added a TTL divide by
1,000 (or 2,000 or 4,000 or 8,000) external circuit to generate very
precise audio test tones from the RF oscillator. The BC-221 had two
output frequency ranges: LOW: 125 to 250 kHz HIGH: 2 to 4 MHz  By using
the appropriate range and divide ratio I could generate 15.625 Hz to 4
kHz (and multiples) with very smooth continuous tuning and great
accuracy (typically better than 0.005%). This was very useful for
adjusting and measuring audio filters and circuits, such as 2125/2295
Hz AFSK terminal units I was using on 2 Meter AM and with SSB rigs for
HF FSK. I could tune up my filters built with 88 mH telephone surplus
toroidial inductors. I could also use the audio source to compare by
ear the beat note between harmonics of my divided-down 5 MHz commercial
surplus precision oven oscillator and RF signals (such as during the
ARRL Frequency Measuring Test).  The anti-backlash gear mechanism,
large dial with high resolution interpolation scale, and well-built
variable capacitor were difficult to find in other commonly available
radio related equipment. In my opinion the BC-221 was a technically
beautiful precision instrument. It was the time-nuts tool of choice for
several decades!
--

Bill Byrom N5BB







On Sun, Feb 12, 2017, at 08:31 PM, Bob Camp wrote:

> Hi

> 

> If you look at a typical BC-221 in use, it goes from “calibrated” in a
> nice warm hut to the back

> of a jeep. It heads out to an ice cold flight line and the
> switch turns
> the batteries back on again.

> It bumps in and out of a batch of B-17’s setting each one up for the

> day’s net frequencies. You

> would be doing very well to hold 50 ppm under those
> circumstances. That
> was indeed adequate

> for the purpose.

> 

> Bob

> 

> 

>> On Feb 12, 2017, at 7:58 PM, Bob Albert via time-nuts > n...@febo.com> wrote:
>> 

>> Well 5 cycles per second is more than accurate enough.  That
>> translates to a 150 Hz error at 30 MHz, definitely negligible for the
>> uses of all these gear.  There was no official Time Nuts group at the
>> time, although many of us had the spirit.  Yet the capability of the
>> BC-221 far exceeded its specification if you could receive WWV.
>> 

>> I noted immediately that zero beat of WWV at 5 MHz was not as precise
>> as at 15 MHz.  In those days there was even a 30 MHz WWV but it got
>> shut down a long time ago.  And there were CHU and JJY.
>> 

>> Bob

>> 

>> 

>>   On Sunday, February 12, 2017 4:02 PM, Dan Rae <dan...@verizon.net>
>>   wrote:
>> 

>> 

>> To put BC-221 things in perspective, the 1 Mc/s reference crystal was
>> adjusted, according to the manual, to within 5 c/s...

>> 

>> Things have come a ways since!

>> 

>> Dan

>> 

>> 

>> _

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>> and follow the instructions there.

>> 

>> 

>> 

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> 

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Re: [time-nuts] Sub-ps delay line

[Bill Byrom]

Have you considered an I/Q phase shifterr? Signals in RF systems are
commonly phase shifted by using an I/Q quadrature modulator.  Here is
how this works:


Apply the source sinewave signal to a quadrature hybrid (or some other
network which produces two outputs with a precise 90 degree phase
relationship between the outputs). Each output goes to the LO port of a
separate double balanced mixer. The IF ports of the two mixers are fed
with two DC signal (one for I control and the other for Q control). The
RF output ports of the two mixers are summed and this produces the
output sinewave signal. This complete system is commonly sold as an "I/Q
modulator" block. By using sine and cosine lookup tables to specify the
I and Q voltages you can generate a vector at any phase on the unit
circle (from a trigonometric point of view). This is the same technique
used to generate most digital modulation (QPSK, 8PSK, QAM, etc.), but in
this case the envelope is kept constant by insuring that the I and Q
signals meet the Pythagorean identity (I^2 + Q^2 = 1, scaled
appropriately). The sine and cosine functions are what is needed to map
the phase angle to I and Q signals which provide a constant amplitude as
the phase is shifted.


Here is an example for an I/Q modulator IC which works from 5 MHz
to 1.6 GHz:
http://www.linear.com/product/LTC5598

--

Bill Byrom N5BB

Tektronix





On Wed, Feb 8, 2017, at 05:25 AM, Mattia Rizzi wrote:

> Hello,

> thank you all for the answers!

> 

> The description I gave in the first email is a simplification of the

> system. The delay line is used to phase-match the clocks of a
> distributed
> measurement system. Each board feature an ADC and a DAC. You
> can see it
> as

> a distributed RF acquisition system, with microwave requirements
> on phase
> matching. The delay line is used ALSO to correctly align the
> clocks for
> the

> ADCs, since each IC has an unknown Aperture Delay (PVT kicks in).

> Unfortunately I cannot change the voltage references to introduces a

> variable delay. That's also why I would like to have a delay
> line rather
> than a set-and-forget solution: I can compensate for PVT of the ADC
> and
> DAC

> as well.

> 

> About temperature variation: LTC6957-1 is excellent, 0.1ps/C of

> propagation

> delay change. I still have to check with Linear if this figure
> is valid
> also if you don't use BOTH (P and N) output clock lines. I'm
> not sure to
> use a balun (such as Minicircuit ADT2-1) for differential-to-single-
> ended
> conversion because I dont want to introduce additional tempco.

> Unfortunately, Mini-circuit has no data about that. The
> varactor itself
> has

> a slight tempco, but the overall tempco should be below 1 ps/C.

> 

> About voltage & supply variations: I'm planning to use a
> dedicate LDO for
> the delay line. LTC6957-1 has a maximum of 50ps/V propagation delay

> variation, I'm expecting to use an LDO with  <1 mV/C of regulation

> stability (LT3045 has less than 100uV over 20 degree variation,
> but it's
> a

> bit expensive). Again, I don't know if the 50ps/V figure is
> still valid
> using only one output, but since LVPECL output stages are done using a
> BJT

> always in the active region, I'm expecting an isolation from the power
> supply voltage.

> 

> @Magnus:

>> My first thought would be to use a pair of couplers before and
>> after the
> delay line and bring it into a mixer to serve as a phase detector such
> that

> you can create a control loop to stabilize delay. This way you get a

> handle

> on the temperature variations.

> 

> Thanks! Do you know a phase detector with such requirements on
> stability?
> I

> checked Mini-circuit but they don't have factory data on the
> stability of
> their products. Also, my signals are clocks rather than pure
> sinewaves.
> 

> @Scott

>> I would also advise you take a look at how well you can maintain your
> system impedance, say 50 Ohms.  For example, I have seen about
> 100's ps
> phase difference on a 10 MHz reference, using one BNC female-female

> coupler

> versus another

> 

> Yes, this is a calibration issue (repeatability) to be
> investigated, but
> since microwave systems have the same issues I hope there's
> already a way
> to how achieve that.

> 

> Thank you!

> 

> cheers,

> Mattia

> 

> 

> 

> 

> 

> 2017-02-07 23:43 GMT+01:00 Magnus Danielson
> <mag...@rubidium.dyndns.org>:
> 

>> Hi,

>> 

>> My first thought would be to use a pair of couplers before and
>> after the
>> delay line and bring it into a mixer to serve as a phase detector
>> such that
>> you can create a control loop to stabilize delay. This 

Re: [time-nuts] Power Problems Lucent KS-24361, L101 & L102

[Bill Hawkins]

 
See
https://www.febo.com/pipermail/time-nuts/2014-October/087670.html

Pin 1 is Plus, pin 2 is Minus to an isolated power supply. All other
pins have no connection.

Hence, no damage.

Schematics are not available, but many people have discovered what it
takes to make them work.

Time nuts is an adventure, but it's best to check the
pipermail/time-nuts archive for previous work.

Good fortune on your quest for knowledge.
Bill Hawkins

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Re: [time-nuts] Wildwood NJ ELoran

[Bill Riches]

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bill Riches
Sent: Friday, February 3, 2017 10:02 PM
To: 'Discussion of precise time and frequency measurement' <time-nuts@febo.com>
Subject: [time-nuts] Wildwood NJ ELoran

Here is a dropbox link to Eloran from xmitter at Wildwood, NJ.  I am 10 miles 
away and it is from my hp SA over a long average.

Spikes on trace were from a GPS power supply that has been corrected.


https://www.dropbox.com/s/gxa85mz00z5l0cp/eloran%20dec%208.jpg?dl=0

73,  Bill, WA2DVU
Cape May
-Original Message-


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[time-nuts] Wildwood NJ ELoran

[Bill Riches]

Here is a dropbox link to Eloran from xmitter at Wildwood, NJ.  I am 10 miles 
away and it is from my hp SA over a long average.


https://www.dropbox.com/s/gxa85mz00z5l0cp/eloran%20dec%208.jpg?dl=0

73,  Bill, WA2DVU
Cape May
-Original Message-


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Re: [time-nuts] eLoran test 6 Feb for almost 2 months

[Bill Riches]

100 khz.

73,

Bill, WA2DVU

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of John Marvin
Sent: Friday, February 3, 2017 1:21 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] eLoran test 6 Feb for almost 2 months

I don't have a Loran receiver, and I live in Colorado. But I'd still like to 
check late at night to see if I can see a signal on my SDR receiver. I tried 
looking at old posts, and did some research online, but the best I can tell is 
that Loran C (and I assume eLoran) is transmitted at around 100 Khz. Anyone 
know precisely what frequency(s) are used by the Wildwood eLOran station?

Regards,

John


On 2/2/2017 11:59 AM, paul swed wrote:
> Well this is nice almost a 2 month long test.
> So if you thought about seeing if you could receive eLoran on your 
> Loran C receiver this is a good opportunity. With respect to the data 
> channel pretty sure none of the receivers we have know or care about it.
>
> The Wildwood, NJ eLoran transmitter will be continuously broadcasting 
> from
> 0900 (EST) on 06 February 2017 through 1200 (EST) on 31 March 2017.
> Wildwood will be broadcasting as 8970 Master and Secondary most of the 
> time but occasionally may operate at other rates.
>
>
>
> Please note that the Loran Data Channel (LDC) will be undergoing 
> testing and may be unavailable or unreliable for short periods of time
>
> from 06-10 February 2017.
>
> Regards
> Paul
> WB8TSL
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Re: [time-nuts] Thunderbolt Harmonics

[Bill Byrom]

I'm trying to be gentle, Rhys. :)  I work with these issues every day at
work. Here are a few more comments. I assume you have the preamplifier
in the spectrum analyzer turned off.


The term "X harmonic" (such as 2nd or 3rd harmonic) means a
multiplication of the fundamental signal by the given factor. So the
term "1st harmonic" isn't used -- that's the fundamental. The 2nd
harmonic is 2X the fundamental, and the 3rd harmonic is 3X the
fundamental. So in your examples you should have said "2nd and 3rd
harmonics):


15 dB attenuation: 2nd harmonic is (-49.13 - +11.40)= -60.53 dBc

20 dB attenuation: 2nd harmonic is (-48.84 - +11.40)= -60.24 dBc

25 dB attenuation: 2nd harmonic is (-48.32 - +11.28)= -59.60 dBc



In nearly all cases it's silly to compare RF powers to 0.01 dB
resolution.  The uncertainty of the signal powers being measured,
cable/connector loss, and instrumentation errors is in nearly all cases
larger than 0.1 dB. Your spectrum analyzer doesn't have separate
amplitude log linearly error specifications, but the total amplitude
error with 20 dB of attenuation is specified as +/- 0.7 dB. So the 2nd
harmonic values are not significantly changing as you change the
attenuation, so the source you are measuring probably has about -60 dBc
2nd harmonic output.


The 3rd harmonic results are going to cause me to wave my hands and make
uncomfortable assumptions. The 20 dB 3rd harmonic level seems to be an
outlier, but there is a possibility that a small amount of instrument
distortion is out of phase with the source signal so that they partially
null. RF measurements ARE magic in some cases. 


The use of the external 20 dB attenuator means that the spectrum
analyzer return loss is isolated from the signal source. What does that
mean? Any RF signal traveling down a cable is slightly reflected by
cable defects, connectors, filters, mixers, and imperfect attenuators or
terminators. The reflected signal is called "return loss" and in some
cases "VSWR" or just "SWR". If you had a perfect 50 ohm termination
(load) at the end of a perfect 50 ohm cable, all of the power sent into
the cable would be absorbed by the load and the return loss would be
infinite. The phase of the reflected signal at the source output
connector depends on the round-trip electrical length of the cable and
the nature of the reflection. The reflection from a short is 180 degrees
different from an open, and other types of load can produce different
reflected phases. By the time the reflection gets back to the source
connector, the phase of the reflected signal can cause the impedance to
appear to be nearly anything (greater or less than 50 ohms and probably
capacitive or inductive). If you change the source frequency there is a
different phase round-trip delay due to the wavelength changing, so in
general the RMS voltage at the source will have some ripple vs
frequency. If you place that 20 dB attenuator directly on the source
output connector, the return loss that the source "sees" is nearly
completely controlled by the quality of the attenuator. Even if the
cable had an open or short at the end, the signal passes both ways
though the attenuator so the return loss must be >40 dB (assuming a very
high quality attenuator). This is the same as saying that the VSWR
(Voltage Standing Wave Ratio) is close to 1. A 40 dB return loss
corresponds to a VSWR of 1.02. If an RF filter doesn't see a low VSWR
load, it may not produce the desired filtering behavior.
--

Bill Byrom N5BB







On Thu, Jan 19, 2017, at 10:48 PM, Rhys D wrote:

> Thanks for the detailed post Bill,

> 

> I'm learning a lot here!

> So the spectrum analyser is indeed a "trap for young players"

> As you guessed, it is a Siglent SSA3000X series analyzer.

> 

> I just looked at the same signal again with varied attenuations
> dialed in
> on the instrument (I am using an external 20dB attenuator from

> minicircuits

> as well)

> 

> Here is what I saw:

> 

> Attenuation  -  Fundamental - 1st Harmonic - 2nd Harmonic

> 15 dB  -   11.40 dB  - 49.13 dB- 51.12 dB

> 20 dB  -   11.40 dB  - 48.84 dB- 56.48 dB

> 25 dB  -   11.28 dB  - 48.32 dB- 49.15 dB

> 

> I guess these numbers mean I can't really trust what I can see on the
> instrument screen?

> 

> By the way, I should just you know that I am not trying to solve a

> specific

> timing problem here, I'm more using it as learning opportunity
> and making
> sure that my setup is the best it can be.

> 

> Thanks again for the input.

> 

> On 20 January 2017 at 12:26, Bill Byrom <t...@radio.sent.com> wrote:

> 

>> You can't trust such low harmonic spurious measurements from a
>> spectrum
>> analyzer unless you know how the spurs change with input level. The

>

Re: [time-nuts] PN/AM and 1.5Hz spur from frequency doubling?

[Bill Byrom]

Since the spur moved in frequency when the amplitude of the 25 MHz
interference changed, my guess is that you have some grounding or cable
leakage issues which are causing the measuring system to produce
erroneous results due to overloading. Do you have all instruments and
sources plugged into the same power line circuit with a common safety
ground? Have you tried moving the equipment cases close to each other
and connecting them with a large gauge wire or strap between the
chassis? A 2 M long RF cable is about a quarter wavelength at 25 MHz,
and it's easy to get ingress if the RF field is high, especially if you
aren't using double shielded cables. Also be sure the 25 MHz transmitter
and transmission line system is well shielded and properly grounded.


What type of cables and connectors are used in the signal path to the
phase noise analyzer?


Has someone performed a field intensity survey in conjunction with the
25 MHz transmitter for safety purposes? You may have a high RF field in
that area, and if the V/m is too great you will have many difficulties.


--

Bill Byrom N5BB







On Fri, Jan 20, 2017, at 01:21 PM, Bob Camp wrote:

> Hi

> 

> I would bet that the spur moving is an indicator of either the 25 MHz
> transmitter carrier or

> modulator drifting in frequency. My guess is that the Maser does not

> drift :)

> 

> Bob

> 

>> On Jan 20, 2017, at 12:22 PM, Anders Wallin
>> <anders.e.e.wal...@gmail.com> wrote:
>> 

>> I made some progress with this issue today.

>> It turns I was using a 75Ohm cable at some point (doh!) which
>> caused a
>> 'forest' of spurs far out. Possibly our other maser has a
>> faulty/cut cable
>> which behaves similarly.

>> The final fix was to turn off our 25 MHz radio time-code
>> transmitter which
>> was causing the strong close-in spur at around 1.5 Hz. It uses a
>> modified
>> DCF77 code where it transmits full power AM-modulated 25MHz
>> carrier for 0,
>> 100ms or 200ms at the start of each second.

>> 

>> Here are PN plots of the 5MHz maser signal, same signal through 75ohm
>> reflective cable to the doubler, and through a 50ohm cable

>> to the doubler which solves the far-out spurs, and finally turning
>> off the
>> radio transmitter. The result is now close to the +6dBc/Hz
>> expected for a
>> doubler.

>> https://goo.gl/photos/qKKvg3SfE1XKxtq17

>> as a time-series of residual phase the switchoff of the time-code

>> transmitter looks like so:

>> https://goo.gl/photos/jNVJK2kj1kGUkSVd9

>> 

>> Finally I tried it with the transmitter on, but reduced coupling
>> into the
>> lab by disconnecting a few monitoring-cables. Strangely this
>> shifts the
>> spur even closer in (close to 1Hz now) and reduces the amplitude as
>> expected
>> https://goo.gl/photos/jG6rxfuC8R2QKchM6

>> 

>> What makes frequency doublers especially sensitive to this kind of

>> interference? The 25MHz carrier is phase-locked to better than 1e-
>> 12 to our
>> masers, so there can't reasonably be a 1-1.5Hz offset in the carrier
>> frequency. What is the interaction? (5th harmonic of 5Mhz mixes with
>> 25MHz?)
>> 

>> Anders

>> 

>> 

>> On Fri, Jan 20, 2017 at 11:06 AM, Anders Wallin
>> <anders.e.e.wal...@gmail.com
>>> wrote:

>> 

>>> Thanks for all the comments so far.

>>> I will try the doubler with another quieter source, and try removing
>>> various potential noise-sources and exchanging cables...

>>> 

>>> I have now uploaded a few more images of the same data to the
>>> shared album
>>> linked in my earlier post.

>>> 

>>> Anders

>>> 

>>> On Thu, Jan 19, 2017 at 10:39 PM, Bill Byrom <t...@radio.sent.com>
>>> wrote:
>>> 

>>>> I see spurs at 50 Hz and harmonics, which I assume are from the
>>>> power
>>>> line at your location. This might be due to an oscillation in the
>>>> power
>>>> supply regulator, leading to nonlinear regulator operation and

>>>> feedthrough of power line ripple. For example, low dropout
>>>> regulators
>>>> can sometimes oscillate when an additional ceramic bypass
>>>> capacitor is
>>>> added due to decreased phase margin in the feedback loop. It's also
>>>> possible that there is too much ripple before the regulator and
>>>> you are
>>>> exceeding the dropout voltage, or that the regulator is going in
>>>> and out
>>>> of an overcurrent condition. Many odd things may happen if the
>>>

Re: [time-nuts] Thunderbolt Harmonics

[Bill Byrom]

You can't trust such low harmonic spurious measurements from a  spectrum
analyzer unless you know how the spurs change with input level. The
second harmonic spur created in an amplifier or mixer inside the
spectrum analyzer input will typically increase by 2 dB for every 1 dB
of input level increase. Anytime you see a frequency converting RF
component (such as the mixer in the input of a spectrum analyzer), it is
nonlinear and will generate harmonics and intermodulation products. All
you need to do is to keep the input level low enough so that the
distortion products generated in the analyzer are below the signals you
are measuring. The best and easiest technique is to increase the input
attenuation by the smallest step available (such as 5 dB or 10 dB) and
checking how the spurious components change.
** If the harmonic or other spurious signal is coming from an external
source, it should not change as the input attenuation changes.
** If the harmonic or other spurious signal is generated inside the
analyzer, it should change relative to the fundamental signal as the
input attenuation changes.
** I'm talking about the harmonics or other spurious signals relative to
the fundamental frequency being displayed. If you remove the input
signal and still see the spur, it's a residual spur created inside the
analyzer unrelated to the input signal.


If you graph fundamental signal displayed amplitude vs changing input
level, you will typically see the following for spurious signals created
by most mixers or amplifiers:
(1) Fundamental signal = slope of 1

(2) Second harmonic signal = slope of 2

(3) Third order intermodulation (sum or different frequencies caused by
mixing of two signals) = slope of 3


For more background, see:

https://en.wikipedia.org/wiki/Third-order_intercept_point



If that is a SiglentSSA3000X series analyzer, here are the spurious
specifications from the datasheet:
** Second harmonic distortion: -65 dBc (above 50 MHz input with
preamplifier off)
 

Note that the second harmonic distortion is only specified at 50 MHz
input and above and at a -30 dBm input power level with the preamplifier
off. For comparison, here are the specifications of a Tektronix RSA507A
portable spectrum analyzer. Disclosure: I work for Tektronix.
** Second harmonic distortion: - 75 dBc (above 40 MHz input,
preamplifier OFF)
** Second harmonic distortion: - 60 dBc (above 40 MHz input,
preamplifier ON)


I'm sure that the reason for a lower limit on the second harmonic
specification is that the results are worse at lower frequencies. So
it's quite possible that the harmonics you see are mainly coming from
the spectrum analyzer input mixer or preamplifier. As I suggested
earlier, try lowering the input level by 5 or 10 dB  and see if the
harmonics go down linearly.
--

Bill Byrom N5BB





On Tue, Jan 17, 2017, at 08:40 PM, Rhys D wrote:

> Hi all,

>  

> Before I start, let me say I'm rather a newbie at this sort of
> stuff so
> please be gentle.

>  

> I was looking at the output of my Trimble Thunderbolt GPSDO and
> was rather
> surprised to see really "loud" harmonics in there. ~ 60dB down
> from the
> 10Mhz signal.

>  

> Can anyone here shed some light on what I am seeing here?

> Surely this isn't what it is supposed to look like? Should I be
> trying to
> filter these before going to my distribution amplifier?

>  

> Thanks for any light you can shed.

>  

> R

>  

>  

> 

>  

> _

> time-nuts mailing list -- time-nuts@febo.com

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Re: [time-nuts] PN/AM and 1.5Hz spur from frequency doubling?

[Bill Byrom]

I see spurs at 50 Hz and harmonics, which I assume are from the power
line at your location. This might be due to an oscillation in the power
supply regulator, leading to nonlinear regulator operation and
feedthrough of power line ripple. For example, low dropout regulators
can sometimes oscillate when an additional ceramic bypass capacitor is
added due to decreased phase margin in the feedback loop. It's also
possible that there is too much ripple before the regulator and you are
exceeding the dropout voltage, or that the regulator is going in and out
of an overcurrent condition. Many odd things may happen if the power
supply regular isn't working properly.


--

Bill Byrom N5BB





> _

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> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

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Re: [time-nuts] Low CostTemperature sensor

[Bill Hawkins]

Perrier,

Google finds a Siemens NI1000 sensor that follows the nickel curve.
Nickel is popular in industrial control for cost, but not as accurate as
platinum. Converting the platinum curve to accurate temperatures
requires a second order equation, but has been done with 0.1% analog
converters.

Digi-key has ZNI devices as surface mount parts. Sparse data said
nothing about a platinum curve.

I'm curious because my former employer did very well selling platinum
RTD sensors, usually 100 ohms at the triple point.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Perry
Sandeen via time-nuts
Sent: Monday, January 16, 2017 9:33 PM
To: time-nuts@febo.com
Subject: [time-nuts] Low CostTemperature sensor

List,
A while back there was much discussion about temperature sensors.
One simple inexpensive one to consider would be the ZNI1000Temperature
sensor.
It's 1K ohms at 0C and it replicates the temperature curve of the Pt 1K
ohm sensors.
It's about $3 from Digi-Key.
FWIW YMMY
Regards,
Perrier
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Re: [time-nuts] wifi with time sync

[Bill Hawkins]

 
I haven't read the entire thread, but this may be relevant. If not, you
know where to find the delete key.

I live in a life care community - one of 450 people in 300 apartments on
3 floors. When I moved in a year ago, I could get Internet from the
house cable, and they provided the modem. I bought wired and wireless
802.11n dual band routers for two apartments, a two bedroom for us and
an alcove for my shop. There was plenty of noise from other such
routers, but no problem within an apartment. I couldn't use a wireless
keyboard, though. The cursor wandered around with the noise.

Last month, a company experienced in wiring hotels for wireless put DSL
to RJ-45 and 11n wireless access points in each apartment on the second
floor, adding 100 transmitters to the mix. DSL with existing phone
wiring was far cheaper than running new cable. The intent was to provide
universal public Wi-Fi for the children of the residents.

They might as well have installed 100 jammers. There were complaints of
unusable cordless phones (most in the 2.4 GHz range) and lost Wi-Fi
connections that simply reverted to the default IP address range and
failed to reconnect.

I got a home copy (this is my home) of InSSIDer software and surveyed
the halls at 2.4 GHz with a Windows 7 laptop (you need a larger screen
to see the signal distribution) I could see 10 to 20 of the new access
points, as well as the occasional excursion to -10 dbm (top of scale) as
nearby routers and printers kicked in. Great stuff.

There are environments where time sync with Wi-Fi hasn't got a chance.

Jim Lux was looking for a COTS solution to time sync, and this might
work in a controlled environment.

Don't even think about consumer radio clocks that sync from unknown
Wi-Fi environments.

Bill Hawkins (John Hawkins son)
bill.i...@pobox.com


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Re: [time-nuts] Lavoie WWV Frequency Comparator available

[Bill Hawkins]

Had one of those before downsizing. Very clever circuit, if you are
describing the vacuum tube unit.

The small CRT does a circular sweep based on the reference standard with
brightness modulated by the strength of the received signal, so that no
rotation of the half bright half dark pattern proves a match.

>From Minnesota, under good conditions, I could see the pattern change
phase between Colorado and Hawaii as propagation conditions changed.

No room for one now, but it was the most interesting WWV receiver I ever
owned.

Disclaimer: Absolutely no relation to Martin - thought you should know
more about its capabilities.

Bill Hawkins


-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Martin
VE3OAT
Sent: Saturday, January 07, 2017 3:40 PM
To: time-nuts@febo.com
Subject: [time-nuts] Lavoie WWV Frequency Comparator available

I have a Lavoie Labs WWV Frequency Comparator that is surplus to my
needs.  It is s/n 450 but is not marked with the model number, although
I believe it is an LA-800D.  I also have a photocopy of the operation
and service manual, including schematic and parts list.

The device gives an oscilloscopic display of the phase difference
between your local frequency standard and the received WWV signal on
either 5 or 15 MHz.

The beast still works although the electrolytics need replacing (symptom
-- one of the power transformers gets very warm after a few hours of
operation).  And it could probably benefit from a proper RF/IF alignment
(I have never bothered to do this).

The unit is too big and heavy to ship by any normal means, so "local
pick up only".  However, I could meet you "half-way", provided it is
within 200 km of Ottawa, Ontario.  Free to a good home.

... Martin  VE3OAT

(near Ottawa, Canada)

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Re: [time-nuts] Line Voltage - USA

[Bill Byrom]

That sounds like a dangerous idea to me. Lightning arrestors at service
entrances are designed to crowbar only for a cycle or so. As mentioned
earlier in this thread, residential distribution in the US nearly always
consists of a center-tapped balanced feed with the center tap grounded.
If you placed a separate AC crowbar on each 120 V leg to neutral, the
first one to trip would momentarily create a higher than normal voltage
(transient and cycle-to-cycle) on the other 120V leg until the
distribution transformer opens (or a wire melts). If the crowbar wasn't
designed correctly you could create a house fire around the service
entrance. I would let the utility company and the National Electric Code
be the guide, as legally required.


You can purchase voltage regulators or line conditioners (the names are
not very precise) which can prevent overvoltage conditions on a circuit
or even the whole house. A UPS or active line conditioner can be used to
provide voltage stability on a cycle to cycle basis. There is no reason
to kill the power to you and your neighbors for what could be many hours
during very cold or hot conditions at night just because the line
voltage is temporarily high at your house. :)
--

Bill Byrom N5BB







On Wed, Jan 4, 2017, at 06:56 PM, Bill Hawkins wrote:

> Wonder if these cases could be used on social media to create enough

> fear that there would be a market for AC crowbars capable of blowing

> line/pole transformer HV fuses? There's a few hits with Google, mostly
> for DC crowbars. Too bad relays are so slow.

> 

> Bill Hawkins


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Re: [time-nuts] Line Voltage - USA

[Bill Hawkins]

Wonder if these cases could be used on social media to create enough
fear that there would be a market for AC crowbars capable of blowing
line/pole transformer HV fuses? There's a few hits with Google, mostly
for DC crowbars. Too bad relays are so slow.

Bill Hawkins


-Original Message-
From: Jeff AC0C
Sent: Wednesday, January 04, 2017 10:42 AM

The electric company in OKC repaired a pole problem at my parents house
there a few years back.  Somehow they managed to hook up the 240 across
a single leg of the 120.  Fried most of the electrical stuff in the
house and caused enough damage to the house to require a complete
rewiring.  Parents lived in a motel for about a month while the work was
done.  The insurance company and the utility were transparent, covering
all costs including replacement with new similar products without issue
(other than the inconvenience).  I think the electric company was
especially glad that a fire did not result and there was no legal action
as a result.

73/jeff/ac0c
www.ac0c.com
alpha-charlie-zero-charlie

-Original Message-
From: Hal Murray
Sent: Wednesday, January 04, 2017 2:42 AM

> Did the utility replace the damaged equipment?

A friend lived in a building when the city crew working on a transformer
put 440 on the line.  It blew out all the electronics in 12 condos -
mostly TVs.
I think toasters and refrigerators were OK.  There wasn't any question
that the city was at fault.  I don't remember how much paperwork they
had to go through to get reimbursed.  It might get sticky for something
like a time-nut with a lot of used gear that may not be easy to replace
at the original price.  (Could be a good excuse to clean up and start
over.)


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